The effect of 6-day courses of terbutaline and ephedrine on the metablic and hemodynamic responses to a 4-hour epinephrine infusion were compared in the same five individuals. Terbutaline suppressed the subsequent lactate response to epinephrine more than ephedrine did. The suppression of blood glucose response to epinephrine was similar for the two drugs. Ephedrine profoundly altered the hemodynamic responses to epinephrine causing significantly higher systolic and diastolic blood pressures and slower pulse. Terbutaline did not alter the systolic blood pressure during subsequent epinephrine infusion, and had less effect than ephedrine on the diastolic pressure and heart rate during the infusion. The effect of terbutaline on physiologic responses to exercise was studied, employing both brief strenuous and prolonged moderate treadmill exercice. Following 6 days of terbutaline the blood glucose and lactate levels during and following exercise were consistently but not markedly reduced. There was no effect on hemodynamic responses or on blood levels of free fatty acids, nor did exercise tolerance appear to be reduced. The 6-day course of terbutaline did not alter the bronchial sensitivity to inhaled methacholine as measured by spirometry. We conclude that subsensitivity is a characteristic response in most tissues to chronic exogenous adrenergic stimulation. The failure to demonstrate altered methacholine sensitivity may indicate that the adrenergic receptors of the bronchial smooth muscles are an exception to this rule, or, more likely, may reflect the difficulty in demonstrating partial bronchial adrenergic blockade in normal individuals.

The response to preseasonal immunotherapy with aqueous grass extract, timothy antigen D, or water-soluble timothy (WST) in alginate was compared in patients sensitive to grass pollen. Injections of antigen D in alginate produced little evidence of clinical or immunologic response. Treatment with aqueous grass extract or WST in alginate, on the other hand, significantly reduced the seasonal rise in grass-specific IgE. Aqueous extract therapy was also associated with a decline in leukocyte sensitivity during the pollen season, while WST treatment produced the greatest rise in hemagglutinating antibodies.

Cardiovascular and metabolic responses to exercise and consecutive epinephrine infusions 24 hours apart were measured in 7 normal individuals before and following a week's administration of ephedrine sulfate. There was evidence of less beta adrenergic response to the second control epinephrine infusion compared to the first control infusion, and the depression of the rise in blood lactate was significantly different. A week of ephedrine produced more profound depression of the beta adrenergic responses to epinephrine with significant differences in the rise in blood glucose and lactate, and the pulse and blood pressure responses. Furthermore, these same responses remained significantly altered when a second epinephrine infusion was performed 36 hours following the last dose of ephedrine. The alterations in the response to epinephrine induced by ephedrine are consistent with the concept of effector cell "subsensitivity," an adaptive response to prolonged excessive stimulation.