Effects of chronic diabetes on the responsiveness to endothelin-1 and other agents of rat atria and thoracic aorta.
1. Plasma endothelin-1 level as well as plasma lipid and glucose levels was markedly elevated in the rats treated with streptozotocin 8 weeks earlier. 2. Positive inotropic response, which was significantly greater than that in the age-matched control, was produced by endothelin-1 in the left atria isolated from diabetic rats. On the other hand, the contractile response of thoracic aorta to endothelin-1 was conversely attenuated in the diabetic rats. Such contrasting effects of diabetes between the atrial and aortic muscles were observed in the responsiveness to other contractile drugs. Endothelium-dependent relaxation in the thoracic aorta was also significantly attenuated in diabetic rats. However, the basal twitch contraction of left atria, the chronotropic responses to endothelin-1, isoproterenol and carbachol and the relaxation of the aorta by papaverine were not affected by diabetes. 3. These results suggest that the contractile responsiveness of atrial and aortic muscles and the endothelial functions significantly alter during diabetes for 8 weeks.
Tada
H
H
Third Department of Internal Medicine, Fukui Medical School, Japan.
Muramatsu
I
I
Nakai
T
T
Kigoshi
S
S
Miyabo
S
S
D000818:Animals; D001013:Aorta, Thoracic / Q000187:drug effects*; D002908:Chronic Disease; D003921:Diabetes Mellitus, Experimental / Q000503:physiopathology*; D016232:Endothelins / Q000494:pharmacology*; D006325:Heart Atria; D066298:In Vitro Techniques; D008297:Male; D009119:Muscle Contraction / Q000187:drug effects; D009200:Myocardial Contraction / Q000187:drug effects*; D051381:Rats; D017207:Rats, Sprague-Dawley; D013268:Stimulation, Chemical; D013311:Streptozocin
D016232:Endothelins; D013311:Streptozocin