ISSN:
1432-1912
Keywords:
Calcitonin gene-related peptide
;
Smooth muscle cells
;
Vas deferens - Membrane currents
;
Ca2+ channel
Source:
Springer Online Journal Archives 1860-2000
Topics:
Medicine
Notes:
Summary Effects of calcitonin gene-related peptide (CGRP), a putative non-adrenergic non-cholinergic neutrotransmitter on the electrical properties of the cell membrane, were investigated in enzymically dispersed smooth muscle cells from rat vas deferens. Under current clamp conditions, CGRP (up to 10−7 M) did not induce significant changes in membrane potentials or input resistance in the resting state. The configurations of action potentials elicited by depolarizing current pulses were also unaffected, except that a prolongation of the duration of the action potentials by a high dose (10−7 M) of CGRP was observed in some of the cells. Under whole cell voltage clamp conditions, the transient and sustained K+ currents, activated by depolarizing voltage-steps, were apparently decreased in the presence of 10−9 to 10−7 M CGRP. The peptide increased the voltage-gated Ca2+ current in cells loaded with 145 mM Cs+ solution in order to block the K+ currents. The voltage-dependency of the peak Ca2+ current was not changed by CGRP. Ba2+ (10.8 mM) was used as a charge carrier for the Ca2+-channel current to clarify further the effects of CGRP on the properties of the current. CGRP (10−8 M) delayed the inactivation time course of the Ca2+-channel current and slowed the recovery from inactivation. The peptide did not affect the steady-state inactivation measured by changing the holding potential. The Ca2+-channel current in the presence of CGRP was suppressed by nicardipine (10−6 M) to the same extent as the current under control conditions. The results suggest that CGRP modifies the L-type Ca2+ channel in smooth muscle cells.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF00169006
Permalink
