Mechanical stimulation increases the activity and expression of cytochrome P450 2C in porcine coronary artery endothelial cells

Elevation of intracellular Ca2+ concentration ([Ca2+]i) in endothelial cells is proposed to be required for generation of vascular actions of endothelium-derived hyperpolarizing factor (EDHF). This study was designed to determine the endothelial Ca2+ source that is important in development of EDHF-mediated vascular actions. In porcine coronary artery precontracted with U-46619, bradykinin (BK) and cyclopiazonic acid (CPA) caused endothelium-dependent relaxations in the presence of N G-nitro-l-arginine (l-NNA). The l-NNA-resistant relaxant responses were inhibited by high K+, indicating an involvement of EDHF. In the presence of Ni2+, which inhibits Ca2+ influx through nonselective cation channels, the BK-induced EDHF relaxant response was greatly diminished and the CPA-induced response was abolished. BK and CPA elicited membrane hyperpolarization of smooth muscle cells of porcine coronary artery. Ni2+ suppressed the hyperpolarizing responses in a manner analogous to removal of extracellular Ca2+. EDHF-mediated relaxations and hyperpolarizations evoked by BK and CPA in porcine coronary artery showed a temporal correlation with the increases in [Ca2+]i in porcine aortic endothelial cells. The extracellular Ca2+-dependent rises in [Ca2+]i in endothelial cells stimulated with BK and CPA were completely blocked by Ni2+. These results suggest that Ca2+ influx into endothelial cells through nonselective cation channels plays a crucial role in the regulation of EDHF.

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Pertussis toxin-sensitive G proteins in regenerated endothelial cells of porcine coronary artery

AJP Heart and Circulatory Physiology ◽

10.1152/ajpheart.1994.267.3.h979 ◽

1994 ◽

Vol 267 (3) ◽

pp. H979-H981 ◽

Cited By ~ 7

Author(s):

T. Shibano ◽

J. Codina ◽

L. Birnbaumer ◽

P. M. Vanhoutte

Keyword(s):

Endothelial Cells ◽

Coronary Artery ◽

G Proteins ◽

Coronary Arteries ◽

Pertussis Toxin ◽

Polyacrylamide Gel Electrophoresis ◽

Sodium Dodecyl ◽

High Cholesterol Diet ◽

Porcine Coronary Artery ◽

Yorkshire Pigs

Endothelium-dependent, pertussis toxin-sensitive relaxations are impaired selectively after regeneration of endothelial cells following balloon denudation of the porcine coronary artery. The present study was designed to examine the hypothesis that there is a difference in G proteins modified by pertussis toxin between regenerated and intact endothelial cells. Yorkshire pigs, fed a high-cholesterol diet, underwent balloon denudation of the endothelium of the left anterior descending coronary arteries (LAD). Four weeks after the denudation the animals were killed to detect G proteins by ADP ribosylation catalyzed with pertussis toxin and [32P]NAD, separated on a urea gradient sodium dodecyl sulfate-polyacrylamide gel electrophoresis. In membrane fractions of endothelial cells obtained from previously denuded LAD, G alpha i-1/G alpha i-3 (41 kDa) and G alpha 1-2 (40 kDa) proteins were labeled. The two bands revealed on the gel were the same as those obtained from intact left circumflex coronary arteries (LCX). However, the intensity of the bands was less prominent in the LAD than the LCX. These results suggest that either a decreased amount or a reduced functionality of Gi proteins in the regenerated endothelial cells may account for the impairment in the pertussis toxin-sensitive relaxations after balloon injury of coronary arteries in the pigs.

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