Peripheral circulatory control of cardiac output in diabetic rats.
Diabetes is believed to be associated with impaired systolic and diastolic function of the heart; however, some investigators have found that diabetic rats have increased cardiac output. We investigated changes in the peripheral circulation that could account for an increased cardiac output in diabetic rats (n = 30), 4 wk after a single tail vein injection of streptozotocin (60 mg/kg), and age-matched control rats (n = 31). Compared with controls, diabetic rats exhibited decreased (P less than 0.05) mean arterial pressure, characteristic aortic impedence, and total peripheral resistance; however, cardiac index and stroke volume index were increased. Aortic compliance, mean circulatory filling pressure, central venous pressure, pressure gradient for venous return, and venous compliance were unchanged in the diabetic rats compared with control. Baseline left ventricular end-diastolic pressure and end-diastolic volume were increased in the diabetic rats. Following a volume load of 30 ml/kg, cardiac index and stroke volume index increased less in the diabetic than in the control rats (35 vs. 102% and 69 vs. 105%, respectively). Thus, even with impaired systolic function, cardiac output is increased or maintained in diabetic rats because of the combination of decreased afterload and maintenance of preload.
Litwin
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SE
Department of Internal Medicine, Tucson Veterans Affairs Medical Center, Arizona 85723.
Raya
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TE
Daugherty
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S
Goldman
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S
D000818:Animals; D001011:Aorta / Q000502:physiology / Q000503:physiopathology*; D001794:Blood Pressure; D001810:Blood Volume; D002302:Cardiac Output; D003921:Diabetes Mellitus, Experimental / Q000503:physiopathology*; D005583:Fourier Analysis; D006339:Heart Rate; D008297:Male; D051381:Rats; D011919:Rats, Inbred Strains; D012016:Reference Values