Effects of cesium on spontaneous rate in right atria isolated from diabetic rats.
Previous studies have shown that streptozotocin (STZ) induced diabetes in rats is associated with a decrease in the spontaneous rate of isolated right atria. Present experiments were designed to determine whether this model of insulin-dependent diabetes mellitus alters the chronotropic actions of cesium (Cs+). Right atrial preparations were isolated from STZ-treated and diluent-treated control rats, and bathed in Krebs-Henseleit buffer at 37 degrees C; dose-dependent (0.2-10 mM) effects of Cs+ were examined by cumulative addition. Preparations isolated from diabetic rats had a slower beating rate before exposure to Cs+, and the negative chronotropic response to this cation was diminished in these tissues. In fact, at concentrations between 2 and 10 mM Cs+, spontaneous rate did not differ between the diabetic and control groups. These data suggest that the hyperpolarization-activated current, I(f), may play a role in the slower spontaneous pacemaker rate observed in right atria isolated from STZ-induced diabetic rats.
Kennedy
R H
RH
Department of Pharmacology and Toxicology, University of Arkansas for Medical Sciences, Little Rock 72205.
Hicks
K K
KK
Stimers
J R
JR
Seifen
E
E
D000818:Animals; D002586:Cesium / Q000494:pharmacology*; D003864:Depression, Chemical; D003921:Diabetes Mellitus, Experimental / Q000503:physiopathology*; D004594:Electrophysiology; D006325:Heart Atria / Q000187:drug effects / Q000503:physiopathology; D006339:Heart Rate / Q000187:drug effects*; D066298:In Vitro Techniques; D015640:Ion Channel Gating / Q000187:drug effects; D008297:Male; D051381:Rats; D017207:Rats, Sprague-Dawley
D002586:Cesium