Coronary vascular ATP-sensitive potassium channels are activated to a greater extent in spontaneously hypertensive rats than in Wistar-Kyoto rats

Kohtaro Numaguchi, Kensuke Egashira, Makoto Sakata, Hiroaki Shimokawa, Akira Takeshita

Research output: Contribution to journalArticle

8 Citations (Scopus)

Abstract

Objective To determine whether opening of coronary vascular adenosine 5'-triphosphate (ATP)-sensitive potassium (K(ATP)) channels is involved in the maintenance of resting coronary flow in hypertrophied hearts. Methods We examined the effects of glibenclamide, a selective inhibitor of K(ATP) channels, on basal coronary vascular tone in Wistar-Kyoto (WKY) rats and spontaneously hypertensive rats (SHRs). Using a Langendorff system, the hearts from WKY rats and SHRs were isolated and perfused with oxygenated Krebs-Henseleit solution at a constant perfusion pressure of 60 and 100 mmHg respectively. Results Basal coronary flow and myocardial oxygen consumption (MVo2) were similar in SHRs and WKY rats. The percentage decreases in coronary flow with glibenclamide at graded doses were greater (P < 0.01) in SHRs than in WKY rats (n = 8), whereas the percentage decreases in MVo2 with glibenclamide were similar in the two groups. The decreases in coronary flow caused by U46619 (a thromboxane A2-mimetic agent) were similar in SHRs and WKY rats (n = 4). The increase in coronary flow caused by pinacidil (a K(ATP) opener) was greater in SHRs than in WKY rats; glibenclamide prevented the pinacidil-induced increase in coronary flow in both SHRs and WKY rats. There was a significant positive correlation between the glibenclamide-induced decrease in coronary flow and the degree of left ventricular hypertrophy (r = 0.54, P < 0.05). Conclusion Our results suggest that the basal opening state of coronary vascular K(ATP) channels is activated to a greater extent in SHRs than WKY rats, which may contribute to the maintenance of basal myocardial perfusion in hypertrophied hearts.

Original languageEnglish
Pages (from-to)183-189
Number of pages7
JournalJournal of hypertension
Volume14
Issue number2
DOIs
Publication statusPublished - Jan 1 1996

All Science Journal Classification (ASJC) codes

  • Internal Medicine
  • Physiology
  • Cardiology and Cardiovascular Medicine

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