INVESTIGADORES
SPERONI AGUIRRE Francisco Jose
artículos
Título:
L, P-/Q- AND T-TYPE Ca2+ CHANNELS IN SMOOTH MUSCLE CELLS FROM HUMAN UMBILICAL ARTERY
Autor/es:
SILVIA SALEMME; ALEJANDRO REBOLLEDO; FRANCISCO SPERONI; SILVANA PETRUCCELLI; VERÓNICA MILESI
Revista:
CELLULAR PHYSIOLOGY AND BIOCHEMISTRY : INTERNATIONAL JOURNAL OF EXPERIMENTAL CELLULAR PHYSIOLOGY, BIOCHEMISTRY, AND PHARMACOLOGY.
Referencias:
Año: 2007 vol. 20 p. 56 - 64
ISSN:
1015-8987
Resumen:
The electrophysiological and
pharmacological properties of Ca2+ current (ICa) were determined by the
whole-cell configuration of the patch-clamp technique in smooth muscle cells
from human umbilical artery. Using 5
mM extracellular Ca2+, depolarizing step pulses from -60
to 50 mV from a holding membrane potential of -80 mV evoked an Ica which
activated at membrane potentials more positive than -50 mV and exhibited a
maximum current density in a range of 10-20 mV. Steady-state inactivation protocols
using a Vtest of 10 mV gave a voltage at one half inactivation and a slope
factor of -35.6 mV and 9.5 mV, respectively. Nifedipine (1 µM), an L-type Ca2+ channels
antagonist, completely inhibited ICa, while the L-type Ca2+ channels agonist
Bay-K 8644 (1 µM) significantly increased ICa amplitude. Moreover, the selective
blocker of P-/Q-type Ca2+ channels ù- agatoxin IVA partially blocked ICa (about 40 % inhibition
at +20 mV by 20 nM). These pharmacological results suggest that L- and
P-/Q-type Ca2+ channels, both nifedipine-sensitive, underlie the ICa registered
using low extracellular Ca2+. The presence of the P-/Q-type Ca2+ channels was
confirmed by immunoblot analysis. When ICa was recorded in a high concentration
(30 mM)
of extracellular Ca2+ or Ba2+ as current carrier, it was evident the presence
of a nifedipine-insensitive component which completely inactivated during the course
of the voltage-step (75 ms) at all potentials tested, and was blocked by the
T-type Ca2+ channels blocker mibefradil (10 µM). Summarizing, this work shows
for the first time the electrophysiological and pharmacological properties of
voltage-activated Ca2+ currents in human umbilical artery smooth muscle cells.