Bufalin promotes the release of noradrenaline from isolated guinea pig vas deferens
Abstract
Bufalin (B), one of the active principles extracted from toad venom, caused a long-lasting contraction of isolated vas deferens of guinea pig at the concentrations of 1.3-9.1 microM.
The B-induced contraction was blocked or even abolished by a pretreatment with phentolamine 10 microM, reserpine 2 (mg/kg) d*2 d, verapamil 1 microM or stored at 4 degrees for 7 d, and was partly inhibited by a pretreatment with bretylium 0.73 mM or cocaine 15 microM, but unaffected by atropine 0.43 microM or cyproheptadine 1 microM.
When the vas deferens was incubated with B, a marked release of NA was observed. This response was prevented by reserpine.
These results suggested that the B-induced contraction of vas deferens might be due to NA released from the adrenergic nerve terminals.
Keywords:
The B-induced contraction was blocked or even abolished by a pretreatment with phentolamine 10 microM, reserpine 2 (mg/kg) d*2 d, verapamil 1 microM or stored at 4 degrees for 7 d, and was partly inhibited by a pretreatment with bretylium 0.73 mM or cocaine 15 microM, but unaffected by atropine 0.43 microM or cyproheptadine 1 microM.
When the vas deferens was incubated with B, a marked release of NA was observed. This response was prevented by reserpine.
These results suggested that the B-induced contraction of vas deferens might be due to NA released from the adrenergic nerve terminals.