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.

Effects of haloperidol on neurotransmitter activity in the rat vas deferens.

1. The effects of haloperidol on the responses of the isolated rat vasa deferentia to catecholamines and ACh were studied. 2.

Effects of clonixin, a non-steroidal analgesic, on the neurotransmission of the vas deferens of the rat.

1. The effect of C1X on the responses to TNS, ACh and NE in the isolated rat vas deferens was studied. 2.

Castration and tolerance induces changes in the levels of the activity of acetylcholinesterase in the isolated vas deferens of the rat.

Changes in the activity of acetylcholinesterase (AChE) of the isolated vas deferens from normal, castrated, morphine and ethanol-tolerant rats were studied. Three days after the termination of treatment with morphine and on the last day of treatment with ethanol, a significant inhibition of the activity of AChE was detected. This reduction in the enzymatic activity persisted in morphine-tolerant rats for 15 days, but not for 30 days, at which time the levels of AChE were determined to be normal.

Mixed actions of hemicholinium at autonomic receptor sites of the rat vas deferens.

1. The effects of hemicholinium (HC-3) on several autonomic agents in the isolated rat vas deferens were investigated. 2.

Ontogenesis of autonomic receptors and AChE activity in the rat vas deferens.

The study was undertaken to obtain some information about the development of the autonomic receptors and the AChE activity in the rat vas deferens. The results suggest that the adrenoceptors were fully developed at birth. The M1-ACh receptors were developed before the M2-ACh receptors.

Presynaptic regulation by ACh of the NE mediated responses in the rat vas deferens.

In the isolated electrically stimulated vas deferens preparation the effect of exogenous acetylcholine (ACh) was studied. It was possible to differentiate two separate sites for the action of ACh. A postsynaptic effect (M1) which is revealed as a sudden decrease in the basal tension of the muscular twitch, antagonized competitively by atropine (pA2 = 8.

Testosterone and tolerance in rat vas deferens.

Testosterone is able to inhibit the development of tolerance in the smooth muscle of the rat vas deferens. Cycloheximide and actinomycin D also inhibit the tolerance to morphine and ethanol in smooth muscle of rat vas deferens. The toxic effect of cycloheximide and actinomycin D do not play roles in the inhibition of tolerance.

Effect of certain drugs in perfused human placenta XII: autacoid antagonism by phenothiazines.

The effects of chlorpromazine, prochlorperazine, and trifluoperazine on the pressor actions of serotonin, angiotensin, and bradykinin in the perfused vessels of full-term human placentas were investigated. A significant inhibition of the effect of serotonin was observed with trifluoperazine and chlorpromazine but not with prochlorperazine. The inhibition is attributed to the ability of phenothiazines to cause adrenergic blockade.

Mass-spectrometric determination of the amino acid sequences in peptides isolated from the protein silk fibroin of Bombyx mori.

Several peptides were isolated from the protein silk fibroin of Bombyx mori by means of ion-exchange chromatography of a chymotryptic digest. The sequences of three of the peptides, Gly-Ala-Gly-Tyr, Gly-Val-Gly-Tyr and Gly-Ala-Gly-Ala-Gly-Ala-Gly-Tyr, were known from previous chemical work, but the sequence of the fourth, Gly-Ala-Gly-Val-Gly-Ala-Gly-Tyr, was previously only partially known. The necessary volatility for mass-spectrometric examination of the peptides was achieved by permethylation of the N-acetyl-peptide methyl ester derivatives.