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The numerous and widespread effects of adenosine provide both an opportunity for the development of novel therapeutic agents acting via adenosine receptors and the challenge of achieving selectivity of action. The feasibility of achieving selectivity is enhanced if receptor subtypes can be identified. Biochemical, functional and receptor-cloning studies are(More)
1 An attempt was made to determine whether the extracellular adenosine receptor that mediates relaxation in the guinea-pig trachea is of the A(1)/R(i) or A(2)/R(a) subtype.2 Dose-response curves to adenosine and a number of 5'- and N(6)-substituted analogues were constructed for the isolated guinea-pig trachea, contracted with carbachol.3 The 5'-substituted(More)
The aim of this study was to determine whether ATP must be hydrolysed to adenosine in order to activate the P1-purinoceptor. Isometric contractions of electrically paced guinea-pig isolated left atria were recorded. Purines evoked negative inotropic responses that were competitively antagonised by theophylline. The order of agonist potency was(More)
The degree of reactivity to noradrenaline of the perfused mesenteric vasculature and the blood pressure of the renal hypertensive rat were correlated. Early (true) supersensitivity was demonstrated for noradrenaline and angiotensin but not for KCl. Later (apparent) hyperreactivity to all three substances was related to an elevated maximal response. The(More)
1. A number of metabolites have been proposed to control the vascular tone of skeletal muscle during exercise. The present study was designed to investigate the role of adenosine in this response by determining the effect of the adenosine receptor antagonist 8-phenyltheophylline. 2. The gracilis muscle of anaesthetized cats was exposed and made to contract(More)
The renal resistance vessels of the mature spontaneously hypertensive rat (SHR) exhibit increased reactivity to vasoconstrictor agonists. This could be a cause or consequence of hypertension. We have compared vascular reactivity in isolated perfused kidneys from 46-day-old SHR and from normotensive control rats. The amplitude of responses in kidneys from(More)
OBJECTIVE This study explores whether the a1 blocker prazosin improves capillarisation, blood flow and muscle performance in chronically ischaemic muscles. DESIGN Rat skeletal muscles were made ischaemic by unilateral ligation of the common iliac artery. The animals received prazosin and muscle blood flow, performance and capillary supply were studied 2(More)
1. Previous studies have shown that 8-phenyltheophylline (8-PT), a non-selective antagonist at adenosine A1- and A2-receptors, can ameliorate the severity of glycerol-induced acute renal failure (ARF) in the rat. In the present study we have examined the effects of an antagonist with selectivity for adenosine A1-receptors(More)
We investigated vascular reactivity in isolated, Tyrode perfused kidneys from male (blood pressure, 222.6 mm Hg) and female (blood pressure, 178.5 mm Hg) spontaneously hypertensive rats (SHR, 4-6 months age) and sex and weight matched normotensive Kyoto Wistar and Wistar control rats. Optimal perfusion flows and basal pressures were similar in sex-matched(More)