Pharmacological actions of substance P in the rat vas deferens.

SP produces two different muscular responses in the isolated vas deferens of the rat. 1) A myotropic, post-synaptic effect that results from stimulation of one subtype of SP receptor, located on the membrane of the smooth muscle (NK-3 receptor). 2) A neurogenic effect at the pre-synaptic level that results from stimulation of another subtype of SP receptor, located on the nerve terminals (NK-1 receptor).

Evidence that dopamine is acting at alpha-adrenoceptors of the rat vas deferens.

In the rat vas deferens, a vast number of experiments have shown that the alpha-adrenoceptors present are of two types: alpha 1 and alpha 2. This series of experiments with the isolated rat vas deferens was designed to probe by pharmacological means, the nature of the responses elicited by neurogenic transmural stimulation and also those responses evoked by exogenous NE and DA. The methodology required the production of chemical denervation, neurotransmitter depletion, and the use of specific adrenoceptor blockers.

Pre- and post-synaptic muscarinic receptors of the rat vas deferens: an update.

The pre- and post-synaptic muscarinic receptors of the rat vas deferens are not M1 since the M1-selective antagonist pirenzepine (PZ) has low affinity for both. On this basis both the pre- and post-synaptic actions of ACh in this preparation seem to be mediated via M2-like muscarinic receptors. The following experimental observations reveal that both responses are mediated by pharmacologically distinct muscarinic receptors.

Neuromodulatory actions of substance P on the muscarinic receptors of the vas deferens of the rat.

The response of post-synaptic neurokinin receptors to SP were not changed by pirenzepine or N-methyl-scopolamine. Atropine led to a slight increase in the EC50 of SP for its post-synaptic neurokinin (NK-A) receptor. In the presence of neostigmine no changes in the Emax and EC50 values of SP for its post- and pre-synaptic receptor site were observed.

Selective antagonism by pirenzepine and N-methyl-scopolamine on muscarinic receptor subtypes of the rat vas deferens.

1. The effects of pirenzepine and N-methyl-scopolamine on the responses to ACh in the isolated rat vas deferens were studied. 2.