Investigation of the subtypes of alpha1-adrenoceptor mediating contractions of rat vas deferens.

1 The subtypes of alpha1-adrenoceptor mediating contractions of rat vas deferens to endogenous and exogenous noradrenaline and to the exogenous agonists methoxamine, phenylephrine and A61603 have been examined. 2 The effects of antagonists on the shape of concentration-response curves, both tonic and phasic, to the four agonists were analysed. Prazosin produced parallel shifts in all cases.

Investigation of the prejunctional alpha2-adrenoceptor mediated actions of MDMA in rat atrium and vas deferens.

1. We have investigated the effects of methylenedioxymethamphetamine (MDMA, 'ecstasy') on peripheral noradrenergic neurotransmission in the rat. 2.

Effects of changes in pH and CO2 on pulmonary arterial wall tension are not endothelium dependent.

We examined the changes in isolated pulmonary artery (PA) wall tension on switching from control conditions (pH 7.38 +/- 0.01, PCO2 32.

Investigation of the subtypes of alpha2-adrenoceptor mediating prejunctional inhibition in rat atrium and cerebral cortex.

We have investigated the subtype of alpha2-adrenoceptor mediating prejunctional inhibition of neurotransmission in rat atrium in comparison with the alpha2-adrenoceptor mediating prejunctional inhibition in rat cerebral cortex. In rat atrium and cerebral cortex, prejunctional alpha2-adrenoceptors were investigated in terms of the ability of alpha2-adrenoceptor antagonists to increase the stimulation-evoked overflow of tritium in tissues pre-incubated with [3H]-noradrenaline. The relatively non-selective alpha2-adrenoceptor antagonist yohimbine and the alpha2D-adrenoceptor selective antagonist BRL 44408 had potencies in rat atrium which were similar to their potencies in rat cerebral cortex.