Experiments were carried out to examine the components of the intracellular second messenger system that is involved in beta 3-adrenoceptor (atypical beta-adrenoceptors)-mediated relaxation in the guinea pig taenia caecum. Propranolol and butoxamine caused competitive antagonism of the relaxant response to isoprenaline. However, propranolol or butoxamine did not significantly affect the relaxan...

1 Dose-response curves for the positive inotropic and chronotropic responses to isoprenaline were obtained in atria from untreated guinea-pigs and those receiving various reserpine pretreatments. 2 Tension responses were unaffected, whereas rate responses were depressed by the lowest dose of reserpine (0.05 mg/kg i.p. at 24 hours). 3 With larger 24 h doses and a 3 day pretreatment, the rate and...

This paper reports experiments on the stereospecificity observed in the monophenolase and diphenolase activities of mushroom tyrosinase. Several enantiomorphs of monophenols and o-diphenols were assayed: L-tyrosine, D,L-tyrosine, D-tyrosine; L-alpha-methyltyrosine, D,L-alpha-methyltyrosine; L-dopa, D,L-dopa, D-dopa; L-alpha-methyldopa, D,L-alpha-methyldopa; L-isoprenaline, D,L-isoprenaline and ...

The changes in plasma level of alpha-atrial natriuretic polypeptide (alpha-ANP) and the relaxing responses to exogenous alpha-ANP of strips of rat aorta pretreated with methoxamine were examined at one, four and eight weeks after myocardial infarction induced by left coronary ligation. Responses to a beta-adrenergic stimulant, isoprenaline, and sodium nitroprusside of the vessel pretreated with...

The sensitivity of the isolated ileum of the rat to catecholamines has been investigated using normal, reserpinized and guanethidine treated animals. Both reserpine and guanethidine treatment produces supersensitivity to adrenaline, noradrenaline and to a greater extent to isoprenaline.

Improvement in the results of tests of ventilatory function in response to a bronchodilator drug, given by inhalation or by injection, is now widely used to indicate the presence of reversible " bronchospasm" (Rossier, 1949; Gilson and Hugh-Jones, 1955; Kennedy and Thursby-Pelham, 1956). Frequent repetition of some of these tests in a small series of patients has revealed an interesting relatio...

to investigate the cardioprotective potential of the aqueous extract of allium cepa linn. bulb in isoprenaline-induced myocardial injury in wistar albino rats. in vitro total phenolic, total flavonoid content and 2, 2’-diphenyl-1-picrylhydrazyl hydrate radical scavenging activity was measured. isoprenaline-induced myocardial injury model was used to evaluate in vivo effect of aqueous extract of...

Aminophylline and isoprenaline, two drugs widely used in the managem2nt of asthma, have a pulmonary vasodilator action as well as a bronchodilator action. If regional pulmonary vasoconstriction in poorly ventilated parts of the lungs is a significant compensatory phenomenon in asthma, the effects of administration of these agents on gas exchange would depend on the relative magnitudes of bronch...