Effect of apamin on responses to BRL 34915, nicorandil and other relaxants in the guinea‐pig taenia caeci
Open Access
- 1 May 1986
- journal article
- research article
- Published by Wiley in British Journal of Pharmacology
- Vol. 88 (1) , 113-120
- https://doi.org/10.1111/j.1476-5381.1986.tb09477.x
Abstract
BRL 34915 (4–64 × 10−7 M), isoprenaline (0.5–32 × 10−8 M) and nicorandil (4–64 × 10−6 M) produced a slowly‐developing relaxation of spontaneous tone of the guinea‐pig taenia caeci; with no after‐contraction on washout. These inhibitory responses were unaffected by apamin (10−7 M). Adenosine triphosphate (0.06‐2 × 10−3 M) and noradrenaline (1–16 × 10−7 M) produced a rapid inhibition of spontaneous tone with a prominent after‐contraction, especially on washout. Both the inhibitory effect and the rebound contraction were abolished by apamin (10−7 M). Exposure to both BRL 34915 (64 × 10−7 M) and to nicorandil (64 × 10−6 M) produced an increase in the 86Rb efflux rate coefficient which was unaffected by apamin (10−7 M). Exposure to isoprenaline (32 × 10−8 M) had no effect on the 86Rb efflux rate coefficient. Exposure to noradrenaline (16 × 10−7 M) produced an increase in the 86Rb efflux rate coefficient which was abolished by apamin (10−7 M). The results confirm that both BRL 34915 and nicorandil are capable of opening potassium channels in smooth muscle but show that the channel is not apamin‐sensitive.This publication has 23 references indexed in Scilit:
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