[Protection against myocardial ischemia by nisoldipine--an experimental study with valinomycin K-sensitive microelectrodes].

Abstract

It has been shown that dihydropyridines exert a cardioprotective effect during experimental ischemia. This effect is reflected in a reduced K-efflux from the ischemic tissue. Recently we have shown that ischemic K-efflux is largely mediated by ATP-dependent K-channels. Using K-selective microelectrodes we studied the effect of nisoldipine on K-efflux during simulated ischemia (guinea pig papillary muscle immersed in paraffin oil; normal Tyrode solution, HEPES buffered, 100% O2-equilibrated, 37 degrees C). While ischemic K-efflux was Ca-dependent in stimulated preparations, it was independent of extracellular Ca in resting preparations. Our results show that nisoldipine leads to an inhibition of ischemic K-efflux during simulated ischemia. In resting preparations this inhibition is not a direct Ca-antagonistic effect, since withdrawal of extracellular Ca does not inhibit ischemic K-efflux but nisoldipine does. We suggest a direct effect of nisoldipine on the KATP channel which is mainly responsible for ischemic K-loss.

• Authors: H Köppel, R Gasser, R Pokan, R Willomitzer, L Cichocki, E Pilger, W Klein
• Journal: Acta medica Austriaca (Acta Med Austriaca) Vol. 25 Issue 3 Pg. 101-5 ( 1998) ISSN: 0303-8173 [Print] Austria
• Vernacular Title: Myokardiale Ischämieprotektion durch Nisoldipin--eine experimentelle Untersuchung mit Valinomycin-K-sensitiven Mikroelektroden.
• PMID: 9816403 (Publication Type: English Abstract, Journal Article)

Chemical References

• Calcium Channel Blockers
• Potassium Channels
• Valinomycin
• Nisoldipine
• Potassium

Topics

• Animals
• Calcium Channel Blockers (pharmacology)
• Culture Techniques
• Electrocardiography (instrumentation)
• Guinea Pigs
• Microelectrodes
• Myocardial Ischemia (physiopathology, prevention & control)
• Nisoldipine (pharmacology)
• Papillary Muscles (drug effects, physiopathology)
• Potassium (metabolism)
• Potassium Channels (drug effects, physiology)
• Valinomycin