Adrenomedullin ( AM) levels are elevated in cardiovascular disease, but little is known of the role of specific receptor components. AM acts via the calcitonin receptor-like receptor (CLR) interacting with a receptor-activity modifying protein ( RAMP). The AM(1) receptor is composed of CLR and RAMP2, and the calcitonin gene-related peptide ( CGRP) receptor of CLR and RAMP1, as determined by molecular and cell-based analysis. This study examines the relevance of RAMP2 in vivo. Transgenic (TG) mice that overexpress RAMP2 in smooth muscle were generated. The role of RAMP2 in the regulation of blood pressure and in vascular function was investigated. Basal blood pressure, acute angiotensin II-raised blood pressure, and cardiovascular properties were similar in wild-type (WT) and TG mice. However, the hypotensive effect of IV AM, unlike CGRP, was enhanced in TG mice (P < 0.05), whereas a negative inotropic action was excluded by left-ventricular pressure-volume analysis. In aorta relaxation studies, TG vessels responded in a more sensitive manner to AM (EC50, 8.0 +/- 1.5 nmol/L) than WT ( EC50, 17.9 +/- 3.6 nmol/ L). These responses were attenuated by the AM receptor antagonist, AM(22-52), such that residual responses were identical in all mice. Remaining relaxations were further inhibited by CGRP receptor antagonists, although neither affected AM responses when given alone. Mesenteric and cutaneous resistance vessels were also more sensitive to AM in TG than WT mice. Thus RAMP2 plays a key role in the sensitivity and potency of AM-induced hypotensive responses via the AM(1) receptor, providing evidence that this receptor is a selective target for novel therapeutic approaches.

The mechanisms by which topical mustard oil causes vasodilatation in the mouse were investigated using the tachykinin NK1 receptor antagonist SR140333 and the calcitonin gene-related peptide (CGRP) antagonist BIBN4096BS, alongside αCGRP or NK1 receptor knockout mice. Blood flow was assessed by laser Doppler flowmetry and plasma extravasation by 125I-albumin accumulation. Mustard oil produced significant plasma extravasation and vasodilatation in wild type mice, although the plasma extravasation was less than that seen with capsaicin whilst the vasodilatation was greater. The plasma extravasation was abolished in tachykinin NK1 knockout mice, whilst the vasodilatation was enhanced. BIBN4096BS was unable to inhibit the vasodilatation in wild type mice but abolished it in the NK1 knockout mice. In αCGRP knockout mice, mustard oil also caused plasma extravasation and vasodilatation, which were both inhibited by treatment with SR140333. These data suggest that both a tachykinin NK1 receptor agonist and a CGRP agonist are active as vasodilators, producing redundancy, requiring blockade of both mediators to prevent vasodilatation.

1 Calcitonin gene-related peptide (CGRP) is a potent microvascular dilator neuropeptide that is considered to play an essential role in neurogenic vasodilatation and in maintaining functional integrity in peripheral tissues. 2 We have examined the effect of the nonpeptide CGRP antagonist BIBN4096BS on responses to CGRP and the structurally related peptide adrenomedullin, AM, in murine isolated aorta and mesentery preparations, and in the cutaneous microvasculature in vivo. 3 We show for the first time that BIBN4096BS is an effective antagonist of CGRP and AM responses in the murine mesenteric and cutaneous microvasculature, and of CGRP in the murine aorta. After local administration, BIBN4096BS selectively inhibits the potentiation of microvascular permeability in the cutaneous microvasculature by CGRP and AM, with no effect on responses induced by other microvascular vasodilators. BIBN4096BS reversed both newly developed and established vasoactive responses induced by CGRP. 4 The ability of CGRP to potentiate plasma extravasation was lost when coinjected with compound 48/80 (where mast cells would be activated to release proteases), but regained when soybean trypsin inhibitor was coinjected with compound 48/80. 5 These results demonstrate that BIBN4096BS is a selective antagonist of responses induced by CGRP and AM in the mouse microvasculature, and CGRP in the mouse aorta. The ability of BIBN4096BS to block an established CGRP microvascular vasodilatation indicates that the sustained vasodilator activity of CGRP is due to the retention of the active intact peptide and the continued involvement of the CGRP receptor. British Journal of Pharmacology (2004) 142, 1091–1098. doi:10.1038/sj.bjp.0705824

Acute neurogenic inflammation is observed after topical application of the TrpV1 agonist capsaicin to the mouse ear. Inflammatory oedema is not detectable in the substance P NK1 receptor knockout mouse, indicating the importance of this receptor in mediating neurogenic oedema formation. However, neurogenic vasodilatation remains not only in the NK1 receptor knockout mouse but also in the CGRP knockout mouse after sensory nerve stimulation. Interestingly, it is abolished when both the CGRP and substance P dilator pathways are blocked. This has led us to suggest that there is a facilitatory interaction between endogenously released CGRP and substance P, such that when both are present there is redundancy in terms of dilator mechanisms. This could be relevant to the apparent maintenance of peripheral vasodilator tone, when either NK1 or CGRP receptor antagonists are given systemically for evaluation as novel therapeutic agents. The relative activity of CGRP and the structurally related non-neuropeptide adrenomedullin have been compared. Adrenomedullin is less potent as a vasodilator, but functionally relevant concentrations can be induced in inflamed skin. Both peptides, as a consequence of their vasodilator activity, influence inflammatory processes (e.g. oedema and cell accumulation) acting through the CGRP receptor. Thus, adrenomedullin can act as a non-neuronally derived CGRP agonist in skin.

Calcitonin gene‐related peptide (CGRP) is a potent microvascular dilator neuropeptide that is considered to play an essential role in neurogenic vasodilatation and in maintaining functional integrity in peripheral tissues. We have examined the effect of the nonpeptide CGRP antagonist BIBN4096BS on responses to CGRP and the structurally related peptide adrenomedullin, AM, in murine isolated aorta and mesentery preparations, and in the cutaneous microvasculature in vivo. We show for the first time that BIBN4096BS is an effective antagonist of CGRP and AM responses in the murine mesenteric and cutaneous microvasculature, and of CGRP in the murine aorta. After local administration, BIBN4096BS selectively inhibits the potentiation of microvascular permeability in the cutaneous microvasculature by CGRP and AM, with no effect on responses induced by other microvascular vasodilators. BIBN4096BS reversed both newly developed and established vasoactive responses induced by CGRP. The ability of CGRP to potentiate plasma extravasation was lost when coinjected with compound 48/80 (where mast cells would be activated to release proteases), but regained when soybean trypsin inhibitor was coinjected with compound 48/80. These results demonstrate that BIBN4096BS is a selective antagonist of responses induced by CGRP and AM in the mouse microvasculature, and CGRP in the mouse aorta. The ability of BIBN4096BS to block an established CGRP microvascular vasodilatation indicates that the sustained vasodilator activity of CGRP is due to the retention of the active intact peptide and the continued involvement of the CGRP receptor. British Journal of Pharmacology (2004) 142, 1091–1098. doi:10.1038/sj.bjp.0705824

This review summarizes the receptor-mediated vascular activities of calcitonin gene-related peptide (CGRP) and the structurally related peptide adrenomedullin (AM). CGRP is a 37-amino acid neuropeptide, primarily released from sensory nerves, whilst AM is produced by stimulated vascular cells, and amylin is secreted from the pancreas. They share vasodilator activity, albeit to varying extents depending on species and tissue. In particular, CGRP has potent activity in the cerebral circulation, which is possibly relevant to the pathology of migraine, whilst vascular sources of AM contribute to dysfunction in cardiovascular disease. Both peptides exhibit potent activity in microvascular beds. All three peptides can act on a family of CGRP receptors that consist of calcitonin receptor-like receptor (CL) linked to one of three receptor activity-modifying proteins (RAMPs) that are essential for functional activity. The association of CL with RAMP1 produces a CGRP receptor, with RAMP2 an AM receptor and with RAMP3 a CGRP/AM receptor. Evidence for the selective activity of the first nonpeptide CGRP antagonist BIBN4096BS for the CGRP receptor is presented. The cardiovascular activity of these peptides in a range of species and in human clinical conditions is detailed, and potential therapeutic applications based on use of antagonists and gene targeting of agonists are discussed.

The use of delta wing vortices as power augmentors, originally proposed for wind energy conversion, has been explored for tidal streams and currents. Its effectiveness has been verified in wind tunnel tests, and design parameters for a vortex turbine rotor have been developed. The stability of a submerged delta wing suspended from a float was investigated in a towing tank, and a system which maintained a stable configuration over a wide range of stream velocities was devised. For a given rotor size, power outputs of 2 to 3 times that available in the free stream are anticipated. Tests at higher Reynolds numbers are needed to establish performance more precisely. The concept seems very promising for small and medium-scale applications.

The concept that NK1 receptors are located pre-junctionally on substance P (SP)-containing nerves, acting as autoreceptors to inhibit SP release, has been suggested, but remains a controversial issue. To further investigate the existence of this receptor on central and peripheral terminals of primary afferent fibres, NK1 receptor knockout mice and an NK1 receptor antagonist were used in nerve-attached tissue preparations. These were the isolated dorsal horn of the spinal cord with dorsal roots attached, and the hairy skin of the hind paw with attached saphenous nerve. The results reveal that in the dorsal horn preparation, basal release of SP is significantly higher in NK1−/− mice than NK1+/+ mice (P<0.05, n=7 mice/strain). However, a difference in SP release evoked in the dorsal horn by electrical stimulation of the dorsal roots or capsaicin application was not observed. In contrast, antidromic electrical stimulation of the saphenous nerve caused a substantially greater release of SP in the skin of NK1−/− mice than in NK1+/+ mice (P<0.05, n=5 to 6 mice/strain). These results provide evidence for the existence of NK1 autoreceptors on sensory nerves in skin, which may be relevant to the modulation of their peripheral pathophysiological effector functions.

The aims of this study were to develop a technique to measure blood flow in the mouse ear and to investigate the nature of the vasodilator mediator(s) involved in the response to capsaicin. The response to capsaicin, applied topically, was investigated in anaesthetized CD1 or Sv129+C57BL/6 wild‐type (+/+) or NK 1 receptor knockout mice (−/−). Blood flow was assessed by laser Doppler flowmetry and oedema formation by 125 I‐albumin accumulation. Capsaicin induced significant increases in blood flow (0.2–200 μg in 20 μl) and oedema (2–200 μg in 20 μl). The oedema response was absent in NK 1 −/− mice and NK 1 +/+mice treated with the selective NK 1 receptor antagonist SR140333 (480 nmol kg −1 ) as expected. Furthermore, the capsaicin‐evoked increase in blood flow was significantly potentiated in the knockout mice (203% of wild‐type response, P <0.05) and wild‐type mice treated with SR140333 (201%, P <0.05). The CGRP receptor antagonist CGRP 8–37 (400 nmol kg −1 ) had no effect on capsaicin‐induced blood flow in NK 1 +/+mice but abolished the increased blood flow to capsaicin in NK 1 −/−, and NK 1 +/+wild‐type mice pre‐treated with SR140333. The results indicate that neurogenic vasodilatation can be measured in the mouse ear. The capsaicin‐induced increased blood flow involves activation of, and possible interactions between, both NK 1 and CGRP 1 receptors. British Journal of Pharmacology (2002) 135 , 356–362; doi: 10.1038/sj.bjp.0704485

The tachykinin neurokinin B (NKB) has been implicated in the hypertension that characterises pre‐eclampsia, a condition where tissue oedema is also observed. The ability of NKB, administered intradermally or intravenously, to induce oedema formation (assessed as plasma extravasation) was examined by extravascular accumulation of intravenously injected 125I‐albumin in wild‐type and tachykinin NK1 receptor knockout mice. Intradermal NKB (30‐300 pmol) caused dose‐dependent plasma extravasation in wild‐type (P < 0.05) but not NK1 knockout mice, indicating an essential role for the NK1 receptor in mediating NKB‐induced skin oedema. Intravenous administration of NKB to wild‐type mice produced plasma extravasation in skin, uterus, liver (P < 0.05) and particularly in the lung (P < 0.01). Surprisingly, the same doses of NKB led to plasma extravasation in the lung and liver of NK1 knockout mice. By comparison, the tachykinin substance P induced only minimal plasma extravasation in the lungs of wild‐type mice. The plasma extravasation produced by NKB in the lungs of NK1 receptor knockout mice was unaffected by treatment with the NK2 receptor antagonist SR48968 (3 mg kg−1), by the NK3 receptor antagonists SR142801 (3 mg kg−1) and SB‐222200 (5 mg kg−1) or by the cyclo‐oxygenase (COX) inhibitor indomethacin (20 mg kg−1). L‐Nitro‐arginine methyl ester (15 mg kg−1), an inhibitor of endothelial nitric oxide synthase (eNOS), produced only a partial inhibition. We conclude that NKB is a potent stimulator of plasma extravasation through two distinct pathways: via activation of NK1 receptors, and via a novel neurokinin receptor‐independent pathway specific to NKB that operates in the mouse lung. These findings are in keeping with a role for NKB in mediating plasma extravasation in diseases such as pre‐eclampsia.

The tachykinin neurokinin-1 (NK1) receptor mediates the vasoactive effects of substance P and related members of the tachykinin family. Substance P acts via the NK1 receptor to mediate increased microvascular permeability leading to oedema formation as confirmed in NK1 receptor knockout mice. In addition there is evidence that neuropeptides such as substance P can have a modulatory effect on the wound-healing process. In this study male and female wild-type and NK1 knockout mice were investigated for their comparative ability to induce acute oedema formation in response to topical application of capsaicin, as measured by the extravasation of intravenous radiolabelled-albumin, and wound healing in response to a cut, as measured by area of wound over the following days. Significant (P<0.001) oedema, approximately three-fold over basal, was induced by capsaicin in both male and female wild-type mice, an indicator of a similar responsiveness irrespective of sex. However, as expected, the oedema was not observed in the knockout mice. Wounding was achieved through a 1-cm full-thickness cut into the interscapular area of dorsal skin. Wound healing was then followed in two different protocols. The wound was left to heal naturally over 14 days in the first protocol and no significant changes in healing were observed in wild-type compared to knockout. In the second protocol, the skin was sutured open for the first 48 h, to prevent the elasticity of the skin from initiating a natural healing process through flap formation. This caused a significant increase in the area of the wound. Despite this, wounds in both wild-type and knockout mice healed in an identical manner that was complete after 17 days. In conclusion, it is shown that deletion of a functional NK1 receptor has little effect on wound healing in response to a simple cut in mouse skin.

The epidemiology and burden of HIV in the developing world are discussed earlier (see chapter 1). Two distinct viruses, HIV types 1 and 2 (HIV-1/HIV-2), cause AIDS. HIV-1 is responsible for the great majority of infections globally, HIV-2 being very rare outside of West Africa. Individual cases of HIV-2 infection have been described in other parts of Africa, Europe, the Americas, and Asia (India), but most people with HIV-2 infection have some epidemiological link to West Africa. This article has been adapted from the forthcoming 5th edition of ABC of AIDS. The book will be available from the BMJ bookshop and at http://www.bmjbooks.com/ Adults and children estimated to be living with HIV/AIDS at end of 2000. UNAIDS estimates that 95% of people living with HIV/AIDS are in developing countries The routes of transmission of HIV-1 and HIV-2 (as described in chapter 1) are the same worldwide, but the relative importance of different modes of transmission differs according to region. In most developing countries, heterosexual transmission is the dominant mode of spread, and mother to child transmission of HIV is much more common than in industrialised countries. Homosexual transmission is rare in Africa, but is more common in South East Asia and central and south America. Transmission associated with injecting drug use is particularly frequent in parts of south and South East Asia and central and south America. Acquisition of infection from contaminated blood remains a problem, especially in parts of sub-Saharan Africa and south Asia; in some countries commercial blood donation acts to amplify the spread of transfusion-transmitted HIV infection, both to the recipients of blood as well as to donors who may become infected through exposure to unsterile equipment. Women and children are at especially high risk for transfusion transmitted HIV infection, the former because of the high incidence …

Capsaicin induces tachykinin NK 1 receptor-dependent neurogenic oedema in the mouse ear and this model has been used to determine the absence of NK 1 receptors in NK 1 knockout (NK 1 -/-) mice [1].We have now simultaneously measured neurogenic vasodilatation and oedema in the ear.Wild-type and NK 1 -/-Sv129+C57BL/6 mice were used in this study.Anaesthesia (urethane, 25% w/v; 100ml/10g) was induced.Oedema was assessed by the accumulation of 125 Ialbumin, and blood flow by laser Doppler flowmetry.Responses were measured for 1 h after topical application of capsaicin to one ear and vehicle to the contralateral ear.Capsaicin induced oedema in wild-type Sv129+C57BL/6 mice (p < 0.001), but not in NK 1 -/-mice, as expected [2].However, neurogenic vasodilatation (p < 0.05) was observed in both wild-type and NK 1 -/-mice, and remained in wild-type mice in the presence of the NK 1 antagonist SR140333 (480 nmol/kg).Interestingly, increased blood flow in the NK 1 -/-mice was significantly (p < 0.05) greater than that in the wild-type mice.It was substantially blocked in NK 1 -/-mice pretreated with the CGRP antagonist CGRP 8-37 (400nmol/kg), or wild-type mice treated with both SR140333 and CGRP 8-37 , but not in wild-type mice treated with CGRP 8-37 alone.The results suggest that neurogenic vasodilatation is a consequence of CGRP and NK 1 receptor mediated responses in the mouse.They also indicate that some form of interaction between functional CGRP and NK 1 receptors may occur.

Breeding and diet of Parea Hemiphaga novaeseelandiae chathamensis were studied in relation to food abundance and quality on Chatham Island from 1991 to 1994. Although pairs were found breeding in all months, they nested predominantly during winter and spring (June‐November). The timing of the nesting season, the proportion of pairs that bred and the number of chicks reared per pair varied between nesting seasons. During the 1992–1993 and 1994–1995 nesting seasons, all pairs nested, and many pairs reared two chicks, often involving clutch overlap (58% of 12 cases in 1992–1993, 37% of eight cases in 1994–1995). In 1993–1994, when fruit was scarce, nesting began 2 months later, only 44% of pairs nested and no pairs attempted to rear a second chick. Prior to and during the productive nesting seasons (1992–1993, 1994–1995), the diet of Parea consisted mainly of fruit, particularly that of Matipo Myrsine chathamica in autumn (March‐May) and Hoho Pseudopanax chathamicus in winter and spring. Nutrient analyses of the main Parea foods showed that the pulp of these fruit were rich in lipids and available carbohydrates compared with those in foliage foods. Heavy fruiting of Matipo and Hoho promoted early nesting and prolonged nesting for 6 months, including nesting during winter.