Aims: To investigate whether metoprolol controlled release/extended release (CR/XL) once daily would improve diastolic and systolic left ventricular function in patients with chronic heart failure and decreased ejection fraction. Methods: In an echocardiographic substudy to the Metoprolol CR/XL Randomized Intervention Trial in Heart Failure (MERIT‐HF), 66 patients were examined three times during a 12‐month period blinded to treatment group, assessing left ventricular dimensions and ejection fraction, and Doppler mitral inflow parameters, all measured in a core laboratory. Results: In the metoprolol CR/XL group left ventricular ejection fraction increased from 0.26 to 0.31 (P = 0.009) after a mean observation period of 10.6 months, and deceleration time of the early mitral filling wave (E) increased from 189 to 246 ms (P = 0.0012), time velocity integral of E‐wave increased from 8.7 to 11.2 cm (P = 0.018), and the duration of the late mitral filling wave (A) increased from 122 to 145 ms (P = 0.014). No significant changes were seen in the placebo group regarding any of these variables. Conclusion: Metoprolol CR/XL once daily in addition to standard therapy improved both diastolic and systolic function in patients with chronic heart failure and decreased ejection fraction. (ECHOCARDIOGRAPHY, Volume 21, April 2004)

A female patient born in 1950 underwent plasma exchange and concomitant drug therapy for 20 yr due to homozygous familial hypercholesterolemia. Plasma exchange reduced total cholesterol levels from 25-30 mmol/L (967-1160 mg/dL) before treatment to 9.5 mmol/ L (363 mg,/dL) with regression of xanthomas and no side effects of long-term treatment. Due to end-stage calcific left ventricular outflow tract obstruction not amenable to standard valve reconstructive surgery, a combined heart-liver transplantation was successfully performed in 1996. She is without symptoms and living a normal life 4 yr after transplantation. Total cholesterol value is normal (4.7 mmol/ L [182 mg/dL]) using a moderate dose of statins. Selective coronary angiography is without signs of graft vascular disease and the liver function is normal.

BACKGROUND:Primary or rescue angioplasty are reperfusion modalities in selected patients with acute myocardial infarction, after initial diagnosis in local hospitals. We sought to evaluate the feasibility and safety of transporting patients to a tertiary care hospital for interventional treatment.MATERIALS AND METHODS:Between January 1999 and April 2000, 50 consecutive patients were included in this prospective observational study. Comparisons were performed between patients admitted to primary angioplasty, either directly (n = 20; group A) or from other hospitals (n = 14; group B), and those transferred for rescue angioplasty (n = 16; group C).RESULTS:No severe complications occurred during interhospital transport. Median time interval from onset of symptoms to hospitalization was comparable between groups. Median time interval from onset of symptoms to balloon inflation in group C (340 minutes) was significantly longer than in groups A and B (181 and 130 minutes). All patients were alive at follow-up after median 230 days. Median echocardiographically determined left ventricular ejection fraction in group A was non-significantly higher (50%) than in groups B and C (43% and 46%).INTERPRETATION:Acute transfer for primary or rescue angioplasty is feasible and safe for selected patients with acute myocardial infarction.

BACKGROUND:Hibernating myocardium may benefit from revascularization. There are several experimental models for acute hibernation. In intact hearts low-flow ischemia causes time-dependent metabolic alterations, termed "metabolic adaptation". In isolated heart preparations metabolic responses to low-flow ischemia vary, and signs of metabolic adaptation are not consistently found. In isolated hearts global ischemia may cause bradycardia unless the hearts are paced. We hypothesized that the lack of consistent metabolic adaptation to low-flow ischemia in isolated hearts might be due to bradycardia during ischemia. In this study we investigated the influence of heart rate on metabolism and function in an isolated heart preparation.METHODS:Isolated blood-perfused piglet hearts were subjected to 120 min 10% flow. In groups A (n=9) and B (n=4) hearts were not paced during ischemia, in groups C (n=5) and D (n=5) hearts were paced at pre-ischemic heart rate during ischemia.RESULTS:Without pacing, heart rate declined to approximately 1/3 during ischemia and anaerobic metabolism showed a slight decline over time. With pacing, production of protons, pCO2 and lactate showed a bell-shaped curve which peaked at 20-25 min of ischemia, followed by a subsequent decline towards the end of ischemia (overall p < 0.001 for all). However, reperfusion revealed impaired recovery of function in paced hearts compared to non-paced hearts (53 +/- 7% vs 77 +/- 4%, p < 0.05) concomitant with higher release of creatine kinase (455 +/- 93 IU/100 g vs 106 +/- 13 IU/100 g, p < 0.01).CONCLUSIONS:When heart rate is allowed to decline during low-flow ischemia in isolated piglet hearts, signs of metabolic adaptation are not evident. When hearts are paced during ischemia time-dependent alterations in anaerobic metabolism occur, resembling observations seen in intact beating hearts. However, paced hearts also show indications of increased cellular injury, indicating that in paced hearts the metabolic consequences are mostly due to increased irreversible cell injury. Thus, the model for acute hibernation with 10% flow in isolated blood-perfused piglet hearts are critically dependent on bradycardia during ischemia.

This article presents the results of a retrospective analysis of the use of beta-blockers and current dosing of these agents in patients with coronary artery disease. While 70 to 78% of patients admitted to Norwegian university hospitals during 1990-1997 for angiographic evaluation of chest pain used beta-blockers, only 43-60% of patients with stable coronary artery disease enrolled in the 4S study in Norway received such treatment. High risk groups such as diabetics and patients with peripheral artery disease were less likely to receive beta-blockers during the early period, but were not treated differentially compared to low risk patients during recent years. Only 15% of patients with congestive heart failure received oral beta-blockers, and only 10.5% intravenous beta-blockade during acute myocardial infarction. The dosing of the most common beta-blockers were low, approximately 50% of doses shown to improve survival after acute myocardial infarction.

There are different well established experimental models of low‐flow ischemia. We examined metabolic variables during reduced coronary blood flow (CBF) in intact pig hearts and isolated neonatal pig hearts, producing similar degrees of postischemic dysfunction without infarction. The isolated hearts were perfused with red blood cell enriched buffer. In eight open‐chest pigs mid‐LAD flow was reduced to 70 % for 60 min, followed by 120 min reperfusion. Myocardial segment lengths were recorded and regional coronary venous blood was sampled. In isolated piglet hearts CBF was reduced to 50 % (n=4), 25 % (nequals;4), and 10% (n=17). Only when flow was reduced to 10 % did hearts show signs of anaerobic metabolism. Mechanical function was recorded by a balloon in the left ventricle and coronary venous blood was sampled. Intact pig hearts showed release of protons, CO< 2 , and lactate which peaked after 5–10 min of ischemia and thereafter stabilized at reduced levels. In contrast, in isolated neonatal hearts exposed to 10 % CBF releases of protons, CO 2 , and lactate were stable during ischemia with no adaptational changes over time. In a separate group (n=4), repetitive biopsies revealed no adaptational changes over time for adenosine triphoshate and creatine phosphate during 10 % CBF. Contractile function was stably reduced during ischemia in both models. Conclusion: During reduced CBF "metabolic adaptation" occurs in intact pig hearts. In contrast, this feature is not present in isolated blood‐perfused piglet hearts. The mechanisms responsible for these differences are uncertain. However, differences in metabolism between adult and neonatal hearts and different loading conditions during ischemia might contribute.

Objectives. This study sought to determine whether omega-3 fatty acids act as hypertension prophylaxis in heart transplant recipients and have an impact on vascular reactivity.Background. Cyclosporine-induced hypertension is probably related to endothelial dysfunction. Suggested vasodilatory mechanisms of omega-3 fatty acids may therefore be particularly beneficial in heart transplant recipients.Methods. Heart transplant recipients were randomized to receive either 4 g of omega-3 fatty acids (treatment group, n = 14) daily or corn oil (placebo group, n = 14) from the fourth postoperative day. Twenty-four hour blood pressure monitoring was performed at day 12 and 1, 2, 3 and 6 months postoperatively. Microvascular endothelium-dependent vasodilation, evaluated by skin laser Doppler perfusion measurements of postocclusive reactive hyperemia, was determined preoperatively and at the end of the study.Results. With comparable characteristics at the time of randomization, blood levels of cyclosporine did not at any point differ between the groups. After 6 months, systolic blood pressure decreased 2 +/- 4 mm Hg (mean a SEM) in the treatment group and increased 17 +/- 4 mm Hg in the placebo group (p < 0.01), whereas diastolic blood pressure increased 10 +/- 3 and 21 +/- 2 mm Hg (p < 0.01), respectively. The decrease in systolic blood pressure was inversely proportional to increases in concentrations of serum eicosapentaenoic and docosahexaenoic acid (p = 0.01). After 6 months, five patients in the treatment group and nine in the placebo group needed additional antihypertensive treatment. Although the endothelial-dependent phase of the reactive hyperemic response remained unchanged in the treatment group, it decreased significantly in the placebo group.Conclusions. Postoperative daily administration of 4 g of omega-3 fatty acids in heart transplant recipients is effective as hypertension prophylaxis, depending on increases in serum eicosapentaenoic and docosahexaenoic acids. Preservation of microvascular endothelial function, demonstrated by a more pronounced response to forearm skin ischemia in the treatment group, may contribute to the hypotensive role of omega-3 fatty acids. (C) 1997 by the American College of Cardiology.

BACKGROUND:Adenosine has several potentially cardioprotective effects. We hypothesized that the effects of endogenous adenosine vary with degree of ischemia and that elevating endogenous levels is protective.METHODS AND RESULTS:Isolated blood-perfused piglet hearts underwent 120 minutes of low-flow ischemia (10% flow) or 90 minutes of zero-flow ischemia, all with 60 minutes of reperfusion. Hearts were treated with either saline, the adenosine receptor blocker 8-sulfophenyltheophylline (8SPT, 300 micromol x L(-1)), or the nucleoside transport inhibitor draflazine (1 micromol x L(-1)). In separate groups, biopsies were obtained before and at the end of ischemia. Compared with saline, 8SPT did not significantly alter functional recovery in either protocol. Draflazine significantly improved percent recovery of left ventricular systolic pressure both in the low-flow protocol (92+/-3% versus 75+/-2% [saline] and 73+/-3% [8SPT], P<.001 for both) and in the zero-flow protocol (76+/-3% versus 59+/-4% [saline] and 46+/-9% [8SPT], P<.05 for both). In the zero-flow protocol, draflazine also significantly reduced ischemic contracture and release of creatine kinase. Tissue adenosine at the end of ischemia was elevated by draflazine compared with saline-treated hearts: after low-flow ischemia to 0.10+/-0.05 versus 0.00+/-0.00 micromol x g(-1) dry wt (P<.05) and after zero-flow ischemia to 1.73+/-0.82 versus 0.15+/-0.03 micromol x g(-1) dry wt (P<.05).CONCLUSIONS:In neonatal porcine hearts, endogenous adenosine produced during ischemia does not influence ischemic injury or functional recovery. Elevating endogenous adenosine by draflazine elicits cardioprotection in both low-flow and zero-flow conditions.

Myocardial infarction appears after 20 min of regional no-flow ischemia in vivo, but only after a much longer duration of global ischemia in isolated hearts. We tested whether repetitive myocardial stretching (RMS), as occurs in segmental ischemia, is involved in the pathogenesis of myocardial cell injury, Furthermore, we evaluated the role of stretch-activated channels by using Gadolinium (Gd3+). Isolated piglet hearts were perfused with red cell enriched Krebs-Henseleit buffer. RMS was induced by inflating a balloon in the left ventricle, using a control system to provide a pressure of 120 mmHg during one-third of the cycle and 0 mmHg during the rest of the cycle, with a frequency 150 per min. Function and metabolism were compared during 2 h of low-flow ischemia (10% of control), with and without RMS, followed by 1 h of reperfusion. Non-RMS hearts were exposed to saline (Isch), or Gd3+ 25 mu mol/l (Gd3+-Isch). During ischemia, left ventricular systolic pressure (LVSP) stabilized in non-RMS hearts, but a further decrease, combined with increased anaerobic metabolism occurred in RMS hearts. After 30 min of reperfusion in the non-stretched hearts, LVSP returned to 77 +/- 4% of control (mean +/- S.E.) in the Isch group, and to 74 +/- 2% in the Gd3+-isch group (between groups; P=N.S.). In hearts exposed to RMS, LVSP returned to only 46 +/- 4% of control (RMS) and to 51 +/- 3% in the Gd3+-RMS group (both P=0.01 nu Isch). The same alterations were seen for LV dP/dt. In RMS hearts, tissue concentrations of ATP were reduced and concentrations of lactate increased, We conclude that stretching of ischemic myocardium severely increases anaerobic metabolism and reduces functional and metabolic recovery Blockade of stretch activated channels by Gd3+ does not prevent this effect. Thus, the reduced recovery induced by RMS is due to factors other than ion fluxes through stretch-activated channels. (C) 1997 Academic Press Limited.

Studies in patients with moderate heart failure have shown a positive relation between atrial size and plasma atrial natriuretic peptide (ANP)(99-126) concentrations; however, the relation of the hormone level and left atrial size and left ventricular function in patients with severe chronic heart failure has not been determined. Fifty-three patients from the Cooperative North Scandinavian Enalapril Survival Study with severe chronic heart failure were evaluated with M-mode echocardiography and determination of plasma concentrations of ANP(99-126). In 35 patients, the plasma level of N-terminal ANP(1-98) was also measured. A significant negative relation was found between ANP(1-98), ANP(99-126), and left atrial diameter (r = -.28, P = .05 and r = -.41, P < .005, respectively). Plasma concentrations of both ANP(1-98) and ANP(99-126) were related to left ventricular systolic function as determined by the systolic time interval index (r = .4, P < .05 and r = .29, P < .05, respectively). A significant improvement of left ventricular systolic function was found in the enalapril group but not in the placebo group. After 6 weeks of therapy, no correlation was found between changes in left atrial size or systolic function or changes in either the ANP(1-98) or ANP(99-126) concentration. The results indicate that high ANP(1-98) or ANP(99-126) plasma concentration is determined by the depressed left ventricular function rather than increased left atrial size in patients with chronic severe heart failure. The findings suggest that the ANP release relation to atrial pressure/atrial size is distorted in severe heart failure.

Different conclusions have been reached with regard to the effect of endothelin (ET-1) on cardiac contractility. We examined systolic and diastolic function in response to constant known concentrations of ET-1 with or without ET-1 induced reductions in coronary flow (CF). Rat hearts (n = 21) were buffer-perfused using constant coronary flow (cCF) or constant perfusion pressure (cPP). Left ventricular function was assessed isovolumically. Addition of ET-1 (10(-9) M) in the cCF group caused a gradual increase in PP from 61 +/- 2 to 165 +/- 6 mmHg (mean +/- SE) (P < 0.01). Within 10 min left ventricular systolic pressure (LVSP) increased from 111 +/- 2 to a maximum of 134 +/- 4 mmHg (P < 0.01) and [LVdP/dt] increased from 1640 +/- 81 to a maximum of 2020 +/- 92 mmHg s-1 (P < 0.01). After 15 min left ventricular end diastolic pressure (LVEDP), a measure of diastolic stiffness (DS), also increased. With ET-1 (10(-8) M), similar haemodynamic alterations appeared more rapidly. In the cPP group, ET-1 (10(-9) M) caused a sharp decrease in CF and LVSP fell from 115 +/- 8 to 62 +/- 12 mmHg at 10 min (P < 0.001). Systolic function remained stable at a reduced level for 1 h. DS did not change. Thus, ET-1 possesses positive inotropic effects and increases diastolic stiffness. Both effects may be masked by vasoconstriction-induced ischaemia.

In the hibernating myocardium contractile function and energy consumption are downregulated in response to reduced coronary blood flow (2, 4, 7 – 9). Thus, the myocardium may survive prolonged periods of reduced blood flow without overt signs of ischemia, and it may regain normal contractile function when blood flow restrictions are terminated. The mechanism for this phenomenon is presently unknown, but to get insight into the mechanism involved, it is important to characterize all aspects of it as closely as possibly. Since a direct comparison of regional contractile pattern in acutely hibernating and stunned myocardium has not been reported, we here present such a comparison. We also relate changes in the regional contractile pattern to alterations in local myocardial oxygen consumption (MVO2).

Nitric oxide (NO) is known to regulate basal coronary blood flow (CBF). The objective of the present study was to examine the importance of NO in CBF regulation at various coronary arterial pressures (CAPs) in vivo. Experiments were performed in 11 open-chest pentobarbitone sodium anesthetized pigs. CAP was reduced in steps by a hydraulic occluder on the mid left anterior descending coronary artery (LAD) before and after a 5-min intracoronary infusion of the inhibitor of NO synthesis, NG-nitro-L-arginine (NOARG, 30 mumol min-1). CAP was recorded and NOARG infused through a catheter inserted into the LAD just distal to the occluder. CBF was measured by Doppler flowmetry on the LAD. NOARG significantly reduced CBF by 11 +/- 4, 20 +/- 5, 10 +/- 3, 15 +/- 4, 19 +/- 2, 25 +/- 4 and 25 +/- 5 mL min-1 100 g-1 (mean +/- SE) at CAPs of 30 (n = 6), 40 (n = 9), 50 (n = 9), 60 (n = 9), 70 (n = 9), 80 (n = 8) and 90 (n = 6) mmHg, respectively. These decrements were not statistically different, but the percentage reductions in CBF after infusion of NOARG were significantly greatest at the lowest CAPs. The slight haemodynamic alterations induced by NOARG could not explain the reductions in CBF. Thus, the reductions in CBF after infusion of NOARG were caused by inhibition of a continuous NO release from the coronary endothelium. Coronary NO contributes significantly to CBF at all CAPs between 30 and 90 mmHg. The pronounced reduction in CBF during NO inhibition at the lower CAPs indicates an important vasodilating role of intact endothelium in a region supplied by a stenosed coronary artery.

The importance of nitric oxide (NO) in coronary blood flow (CBF) regulation was examined in anesthetized pigs. NO synthesis was inhibited by intracoronary infusion of NG-monomethyl-L-arginine (L-NMMA) or NG-nitro-L-arginine (L-NNA). L-NMMA (30 mumol/min) reduced CBF (Doppler flowmetry) by 16.3% (13.1-20.2%; P < 0.001) and L-NNA (30 mumol/min) by 16.1% (13.9-18.9%; P < 0.001). During NO blockade, myocardial oxygen consumption was unaltered as an increase in oxygen extraction occurred due to a reduced partial pressure of oxygen and oxygen saturation in blood from the anterior interventricular vein. L-Arginine completely reestablished CBF after giving L-NMMA, but not after giving L-NNA. L-NNA reduced the coronary flow response to ADP by 66-83%, whereas the selected dose of L-NMMA did not affect it. The flow response to adenosine was not affected by either L-NMMA or L-NNA. L-NNA reduced reactive hyperemia after occluding the left anterior descending coronary artery for 10 and 30 s but not for 120 s. Our data show that NO produced in the coronary endothelium plays an important role in CBF regulation in vivo, accounting for approximately 16% of CBF and a major part of the flow response to ADP. NO also contributes to reactive hyperemia after brief, but not longer, ischemic periods.

Left ventricular (LV) function and plasma levels of cardiovascular hormones were examined in patients with severe chronic congestive heart failure (CHF), randomized to placebo or enalapril, in addition to conventional therapy. M-mode echocardiography and plasma hormone concentrations were available at baseline and after 6 weeks of treatment. There was a significant relationship between LV systolic function and levels of angiotensin-II and norepinephrine. Enalapril increased LV fractional shortening (FS%) (13.3 +/- 5.6 to 15.4 +/- 5.8, p < 0.05) and decreased the systolic time interval index (0.58 +/- 0.14 to 0.48 +/- 0.15, p < 0.05) concurrent with a significant decrease in angiotensin-converting enzyme activity and in aldosterone, angiotensin-II, and norepinephrine concentrations after 6 weeks. No changes were found in the placebo group. However, there was no direct relationship between the amount of change in neurohormones and improvement in LV function after 6 weeks. These findings indicate that in patients with severe chronic CHF, severe LV systolic dysfunction is associated with high plasma levels of angiotensin-II and norepinephrine, which can be favorably modified by enalapril. This may be of importance for prolonging life in severe heart failure. The lack of relationship between changes in individual hormones and systolic function suggests complex dynamic interaction. It is, therefore, not sufficient to predict changes in LV function by measuring changes in only one hormone.

It has not been determined previously whether patients with severe chronic congestive heart failure differ in demographic characteristics with respect to left ventricular systolic dysfunction (LVD). In patients with severe chronic congestive heart failure in NYHA IV, an optional protocol in the CONSENSUS-I trial was designed to ascertain whether there were any differences in patient characteristics regarding the degree of LVD defined as left ventricular fractional shortening (FS). A subgroup of 54 patients from the CONSENSUS-I trial were evaluated with M-mode echocardiography. Patients with FS above median (14%) were older (74 +/- 7 vs. 68 +/- 7, p < 0.01), more often female (48 vs. 15%, p < 0.05) and had lower heart rates (77 +/- 15 vs. 95 +/- 17, p < 0.01). Analysis of the 2-year follow-up from the end of the trial was also performed. In the placebo group, patients with FS > 14% had significantly better prognosis than patients with FS < 14%. In the enalapril-treated group no such difference in survival was seen. The difference between the original treatment groups remained, despite the fact that treatment with enalapril was then made available to all surviving patients. In conclusion, patients with advanced chronic congestive heart failure and less severe LVD have different demographic characteristics than patients with more severe LVD. In the placebo group, but not in the enalapril group, prognosis was better in patients with less severe LVD.

OBJECTIVE ATP gated potassium (KATP) channels and adenosine are of crucial importance in coronary blood flow regulation and activation of KATP channels and adenosine receptor stimulation protect against infarction and development of stunning. The aim of this study was to test the hypothesis that opening of KATP channels and adenosine receptor stimulation are involved in perfusion-contraction matching, in acute hibernation, and in recovery after reperfusion. METHODS 30 isolated piglet hearts (2-10 d old) and 20 isolated rabbit hearts were studied. The isolated piglet hearts were perfused with modified Krebs Henseleit (KH) solution enriched by washed human red blood cells; the isolated rabbit hearts were perfused with modified KH buffer. The effects of the KATP channel opener aprikalim (1 microM), the KATP channel antagonist glibenclamide (30 microM), and the adenosine receptor antagonist 8-(p-sulphophenyl)theophylline (SPT, 300 microM) on 2 h of low flow (10%) ischaemia and 1 h reperfusion were compared with saline in the piglet hearts. The effects of aprikalim (1 microM), glibenclamide (30 microM), and saline during 90 min of low flow (10%) ischaemia followed by 1 h reperfusion were also examined in the isolated rabbit hearts. RESULTS At constant coronary flow aprikalim reduced perfusion pressure from 53(SEM 5) to 25(1) mm Hg (p < 0.001) in piglet hearts and from 55(5) to 39(5) mm Hg (p < 0.05) in rabbit hearts. Glibenclamide increased perfusion pressure from 47(5) to 61(6) mm Hg (p < 0.01) in piglet hearts and from 45(4) to 81(5) mm Hg (p < 0.001) in rabbit hearts. SPT increased perfusion pressure from 55(6) to 67(6) mm Hg (p < 0.05) in piglet hearts. Left ventricular systolic pressure remained unchanged in both models. During stepwise reductions in coronary flow a parallel stepwise reduction in left ventricular systolic pressure was observed in all groups. At 2 h of low flow ischaemia systolic pressure was 39(4)%, 37(5)%, 41(4)%, and 37(3)% of control for hearts treated with saline aprikalim, glibenclamide, and SPT, respectively. During the low flow period systolic pressure and MVO2 stabilised. An almost identical pattern occurred in rabbit hearts. After 30 min of recovery of piglet hearts left ventricular systolic pressure increased to 78(5)% (saline), 74(5)% (aprikalim), 84(5)% (glibenclamide), and 77(4)% (SPT) of control. The recovery as percentage of control in rabbit hearts was 63(11) (saline), 69(8) (aprikalim) and 56(13) (glibenclamide). CONCLUSION Coronary vascular tone is highly responsive to KATP channel modulation and adenosine receptor blockade. KATP channels do not modulate either perfusion-contraction matching or acute hibernation and functional recovery during reperfusion in the red blood cell perfused piglet heart or the crystalloid perfused rabbit hearts. Moreover, adenosine receptor antagonism does not affect these phenomena in piglet hearts.

OBJECTIVE:Endothelin is increased in plasma following myocardial infarction. Whether brief periods of myocardial ischaemia not leading to myocardial infarction increase plasma endothelin is not known. Thus, the present study was designed to examine cardiac endothelin balance in association with a 10 min coronary artery occlusion followed by reperfusion.METHODS:Venous blood was selectively sampled from the transiently ischaemic myocardium using a shunt between the anterior interventricular vein and the right atrium in eight pentobarbitone anaesthetised pigs. Flow in the shunt was measured with a Doppler flow probe. Arterial blood was drawn from the aortic arch. Plasma endothelin was measured using an Endothelin 1-21 specific [125I] assay system. This assay system has no cross reactivity with big endothlin.RESULTS:A net cardiac endothelin uptake of 0.7(0.3-1.4) fmol.min-1 x g-1 (median, 95% confidence interval) in the control period shifted to a net release during the first 10 min of reperfusion. The release reached a maximum of 2.8(0.4-6.0) fmol.min-1 x g-1 after 1.5 min of reperfusion. Cardiac venous endothelin concentration increased from 3.4(2.5-4.8) to 4.4(3.6-6.9) and 4.4(3.6-6.6) fmol.ml-1 at 1.5 and 5 min of reperfusion, respectively (p < 0.001 for both). Arterial endothelin concentration decreased from 4.8(3.9-6.1) to 2.7(2.4-4.3) fmol.ml-1 at 10 min of reperfusion (p < 0.001).CONCLUSION:Endothelin is released from the heart for several minutes during reperfusion following a brief coronary artery occlusion.