Characterization of T-type calcium current and its contribution to electrical activity in rabbit urethra

Rabbit urethral smooth muscle cells were studied at 37 degrees C by using the amphotericin B perforated-patch configuration of the patch-clamp technique, using Cs+-rich pipette solutions. Two components of current, with electrophysiological and pharmacological properties typical of T- and L-type Ca2...

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Bibliographic Details
Published in:American Journal of Physiology: Cell Physiology 2004-05, Vol.55 (5), p.C1078-C1088
Main Authors: BRADLEY, J. E, ANDERSON, U. A, WOOLSEY, S. M, THORNBURY, K. D, MCHALE, N. G, HOLLYWOOD, M. A
Format: Article
Language:English
Subjects:
Biological and medical sciences
Calcium
Cell physiology
Cellular biology
Drug therapy
Fundamental and applied biological sciences. Psychology
Membrane and intracellular transports
Molecular and cellular biology
Rabbits
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Summary:Rabbit urethral smooth muscle cells were studied at 37 degrees C by using the amphotericin B perforated-patch configuration of the patch-clamp technique, using Cs+-rich pipette solutions. Two components of current, with electrophysiological and pharmacological properties typical of T- and L-type Ca2+ currents, were recorded. Fitting steady-state inactivation curves for the L current with a Boltzmann equation yielded a V1/2 of -41 +/- 3 mV. In contrast, the T current inactivated with a V1/2 of -76 +/- 2 mV. The L currents were reduced by nifedipine (IC50 = 225 +/- 84 nM), Ni2+ (IC50 = 324 +/- 74 microM), and mibefradil (IC50 = 2.6 +/- 1.1 microM) but were enhanced when external Ca2+ was substituted with Ba2+. The T current was little affected by nifedipine at concentrations
ISSN:0363-6143
1522-1563