Potassium currents in cultured human pulmonary arterial smooth
muscle cells.
Peng, Wei, Sv Karwande, John R Hoidal, and Imad S. Farrukh.
Division of Respiratory, Critical Care and Occupational Pulmonary
Medicine, Department of Medicine, and Division of Cardiothoracic
Surgery, Department of Surgery*, the Veterans Affairs Medical Center
and University of Utah Health Science Center, Salt Lake City, Utah,
84132
APStracts 2:0530A, 1995.
In this study, using whole-cell and single-channel configurations of
the patch-clamp technique, we characterized potassium currents (IK)
in cultured human pulmonary arterial smooth muscle cells (HPSMC). The
net whole-cell outward membrane current (IKo) was activated at
potentials positive to -60 mV. One component of IKo, IK(dr), was
inhibited by 4-aminopyridine (4-AP) and large concentrations of
tetraethylammonium (TEA), but was Ca++ and charybdotoxin (CTX)
insensitive. The other component of IKo, IK(Ca), was voltage- and
Ca++-dependent, and was inhibited by CTX and low concentrations of
TEA. Activation of IKo in single channel recordings was voltage
-dependent and demonstrated a high-conductance channel (245 +/- 2 pS)
that was Ca++ and CTX sensitive (IK(Ca)), and a low-conductance
channel (109 +/- 2 pS) that was inhibited with 4-AP (Ikdr) but was
insensitive to low concentrations of TEA or to an increase in
[Ca++]i. In isolated pulmonary arterial rings TEA and 4-AP caused an
additive increase in arterial tension. To our knowledge these data
provide the first characterization of the IK in HPSMC, and indicate
that IK(Ca) and IKdr play an important role in maintaining pulmonary
vascular tone. The presented data confirms previous observation in
PSMC of animal models.
Received 10 July 1995; accepted in final form 16 November 1995.
APS Manuscript Number A741-5.
Article publication pending Journal of Applied Physiology.
ISSN 1080-4757 Copyright 1995 The American Physiological Society.
Published in APStracts on 8 December 95