Faculty Collaboration Database

A Ca(2+)-dependent K+ current is enhanced in arterial membranes of hypertensive rats. Hypertension 1992 Apr;19(4):301-7

Date

04/11/1992

Pubmed ID

1555863

DOI

10.1161/01.hyp.19.4.301

Scopus ID

2-s2.0-0026717465 (requires institutional sign-in at Scopus site)   91 Citations

Abstract

This study was designed to investigate the role and regulation of arterial membrane K+ channels in hypertension. Aortic segments from normotensive Wistar-Kyoto (WKY) rats and spontaneously hypertensive rats (SHR) were suspended for isometric tension recording. In other experiments, proximal aortic segments (PS) (exposed to high pressure) and distal aortic segments (DS) (exposed to lower pressure) were removed from surgically coarcted Sprague-Dawley rats and similarly prepared. Aortas from SHR and PS dose-dependently contracted to the K+ channel blocker tetraethylammonium (TEA) (0.1-10 mM), and this contraction was abolished by preincubation with 0.1 microM nifedipine. In contrast, the same concentrations of TEA did not contract either WKY or DS aortas. Since block of K+ channels by TEA had a different effect on aortic segments exposed to high versus low blood pressure, we compared whole-cell K+ currents in isolated vascular cells from the same aortas. The reversal potentials of depolarization-induced outward currents in WKY, SHR, DS, and PS aortic cells showed a Nernst relation to external K+ concentration indicative of selective K+ permeability. TEA (1 and 10 mM) was equipotent in blocking these K+ currents in patch-clamped cells from all aortic preparations, suggesting that the lack of TEA-induced contractions in WKY and DS aortas was not due to an absence of TEA-sensitive K+ channels in these arterial membranes. However, when the Ca2+ ionophore A23187 (10 microM) was used to increase the level of cytosolic Ca2+ in patch-clamped cells, the K+ current density in SHR and PS aortic cells was twofold or more higher than in WKY and DS cells.(ABSTRACT TRUNCATED AT 250 WORDS)

Author List

Rusch NJ, De Lucena RG, Wooldridge TA, England SK, Cowley AW Jr

Author

Allen W. Cowley Jr PhD Professor in the Physiology department at Medical College of Wisconsin

MESH terms used to index this publication - Major topics in bold

Animals
Aorta
Calcimycin
Calcium
Cell Membrane Permeability
Dose-Response Relationship, Drug
Muscle Contraction
Muscle, Smooth, Vascular
Nifedipine
Potassium
Rats
Rats, Inbred SHR
Rats, Inbred WKY
Tetraethylammonium
Tetraethylammonium Compounds