Effects of tetrandrine o KCl-, CaCl2- and norepinephrine-induced contractions of isolated rabbit main pulmonary arteries
Abstract
Like verapamil, the inhibitory intensities of tetrandrine on contractions of strips of rabbit pulmonary arteries (RPA) induced by KCl (40 mmol/L), CaCl2 (2 mmol/L) and norepinephrine (0.01 mmol/L) were in the following order: KCl>CaCl2>NE. Both verapamil and tetrandrine reduced KCl- and CaCl2-induced contractions of RPA more readily than they did in NE-induced contractions. However, the inhibitory effect of papaverine on the contractile responses to KCl-induced RPA strips was the same as to NE-induced ones and less effective than NE in CaCl2-induced contractions. The results indicate that tetrandrine is a calcium channel blocker.
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