Potential-dependent calcium channels in rabbit jejunum.

ABSTRACT

Potential-dependent calcium channels have been studied in the isolated rabbit jejunum. A biphasic response was observed, a transient and rapid contraction followed by partial relaxation and a sustained contraction attaining a plateau state. These are similar to the phasic and tonic responses observed in the isolated smooth muscles of other species. Both the responses are susceptible to blockade by the calcium antagonists bepridil, diltiazem, nifedipine, PN 200-110 (isradipine), and verapamil. Two calcium pools or the presence of two channels affecting the two responses are proposed.