Effects of heptanol on the neurogenic and myogenic contractions of the guinea-pig vas deferens.
1. The effects of the putative gap junction uncoupler, 1-heptanol, on the neurogenic and myogenic contractile responses of guinea-pig vas deferens were studied in vitro. 2. Superfusion of 2.0 mM heptanol for 20-30 min produced the following reversible changes in the biphasic neurogenic contractile response (8 trials): (i) suppression of both phases; (ii) delayed development of both the first as well as the second phase, accompanied by complete temporal separation of the two phases; (iii) prominent oscillations of force during the second (noradrenergic) phase only. 3. To eliminate prejunctional effects of heptanol, myogenic contractions were evoked by field stimulation of the vas in the presence of suramin (200 microM) and prazosin (1 microM). Heptanol (2.0 mM) abolished these contractions reversibly. 4. These results show that (i) heptanol inhibits both excitatory junction potential (EJP)-dependent and non EJP-dependent contractions of the vas; (ii) a postjunctional site of action of heptanol, probably intercellular uncoupling of smooth muscle cells, contributes to the inhibition of contraction.
Venkateswarlu
K
K
School of Biomedical Engineering, Indian Institute of Technology, Powai, Mumbai.
Dange
S Y
SY
Manchanda
R
R
D000255:Adenosine Triphosphate / Q000494:pharmacology; D000316:Adrenergic alpha-Agonists / Q000494:pharmacology; D000317:Adrenergic alpha-Antagonists / Q000494:pharmacology; D000818:Animals; D004558:Electric Stimulation; D006168:Guinea Pigs; D019850:Heptanol / Q000494:pharmacology*; D007001:Hypogastric Plexus / Q000187:drug effects / Q000502:physiology; D066298:In Vitro Techniques; D008297:Male; D009119:Muscle Contraction / Q000187:drug effects*; D009130:Muscle, Smooth / Q000187:drug effects* / Q000294:innervation; D009638:Norepinephrine / Q000494:pharmacology; D011224:Prazosin / Q000494:pharmacology; D058919:Purinergic P2 Receptor Antagonists; D013498:Suramin / Q000494:pharmacology; D014649:Vas Deferens / Q000187:drug effects* / Q000294:innervation / Q000502:physiology
D000316:Adrenergic alpha-Agonists; D000317:Adrenergic alpha-Antagonists; D058919:Purinergic P2 Receptor Antagonists; D013498:Suramin; D019850:Heptanol; D000255:Adenosine Triphosphate; D009638:Norepinephrine; D011224:Prazosin