Unique effect of tetrapentylammonium ions on sympathetic transmission in rat vas deferens

Authors: Huang Y.; Lau C.W.

Source: Journal of Autonomic Pharmacology, Volume 18, Number 3, June 1998 , pp. 189-194(6)

Buy & download fulltext article:

Price: $48.00 plus tax (Refund Policy)

Abstract:

Summary •

Effects of tetrapentylammonium ions (TPA⁺) on contractile responses induced by electric field stimulation and by exogenous agonist such as noradrenaline, ATP and high K⁺ were examined in the isolated epididymal half of the rat vas deferens.

•

The electrically evoked monophasic contractions (0.5 Hz, 1 ms pulse duration, 40 V) were potentiated by TPA⁺ at low concentrations (1–3

M) and inhibited by TPA⁺ at a concentration greater than 10

•

TPA⁺ (0.3-3

M) potentiated the contractile responses induced by noradrenaline and ATP, whilst, TPA⁺ (10

M) concentration-dependently reduced the agonist-induced contractions.

•

TPA⁺ (0.3

M) potentiated 30 mM K⁺ -Induced phasic contraction which was inhibited by pretreatment with alpha

-methylene ATP (3

M) and prazosin (3

M).

•

TPA⁺ (10-300

M) reduced the contractions induced by 100 mM extracellular K⁺ while TBA⁺ and TEA⁺ had no effect.

•

The present results show that TPA⁺ at low concentrations may act at prejunctional nerve membranes to enhance release of contractile transmitters and act as a putative K⁺ channel blocker at postjunctional membranes to increase muscle contractility in rat vas deferens; whilst at high concentrations TPA⁺ mainly acts on smooth muscle probably as a non-selective relaxant against the agonist-induced contraction probably through inhibition of Ca²⁺ influx; this inhibitory effect appears unique for TPA⁺ since TEA⁺ and TBA⁺ did not induce muscle relaxation.

Document Type: Research article

DOI: http://dx.doi.org/10.1046/j.1365-2680.1998.1830189.x

Affiliations: 1: Department of Physiology, Faculty of Medicine, Chinese University of Hong Kong, Shatin, Hong Kong, China

Publication date: 1998-06-01