The effects of uptake1 on alpha-adrenoceptor antagonist potency in dog saphenous vein.

1 The effects of alpha-adrenoceptor antagonists on contractile responses to noradrenaline and methoxamine were examined in isolated saphenous vein strips of the dog. 2 Phentolamine, labetalol and thymoxamine antagonized responses to methoxamine to a greater extent than responses to noradrenaline. 3 Cocaine (3.

A proposed mechanism for the biphasic vasoconstrictor responses to 5-hydroxytryptamine and methysergide in the rabbit ear artery.

Rabbit ear arteries were isolated and perfused at a constant flow rate so that the perfusate flowed into the fluid bathing the adventitial surface of the artery. Submaximal doses of intraluminally applied noradrenaline injected as a bolus into the perfusion fluid produced transient monophasic vascoconstrictor responses. In contrast, similarly administered 5-hydroxytryptamine (5-HT) or methysergide caused prolonged biphasic vascoconstrictor responses.

Receptors for 5-hydroxytryptamine and noradrenaline in rabbit isolated ear artery and aorta.

5-Hydroxytryptamine (5-HT) is thought to be implicated in the vascular disturbances of the external carotid artery bed associated with migraine. As part of a study of the pharmacology of some 5-HT antagonists used in the treatment of migraine we have examined the interactions of these drugs with 5-HT and noradrenaline in rabbit isolated ear artery and aortic strip. The results provide new information on the distribution of 5-HT-receptors in these preparations.

Decamethonium in the perfused and immersed rat diaphragm.

1 The water content and mannitol space of rat diaphragms which were perfused through the inferior vena cava was increased compared with immersed diaphragms. The potassium content of both preparations, when expressed in terms of dry weight, was maintained at similar values to that found in vivo. 2 Despite the application of a constant concentration of decamethonium, a steady level of neuromuscular block was not obtained in either the perfused or immersed rat diaphragm.