Decreased Heart Rate and Plasma Catecholahines During Late Pregnancy in Streptozotocin-Induced Diabetic Rats Without Change in Maternal Blood Pressure

Abstract

The aim of this study was to determine if maternal hypertension and/or cardiac dysfunction were involved in the reduction of the uteroplacental blood flow in steptozotocin-induced diabetic pregnant rats (40mg/kg i.V.) and the role of circulating catecholamines in the development of these eventual cardiovascular disturbances. No change in arterial blood pressure was observed in diabetic rats compared to controls whereas treatment of diabetics rats with insulin induced a significant (p<0.05) hypotension. There was a significant decrease of heart rate (p<0.05) and plasma norepinephrine (p<0.001) and epinephrine (p<0.01) in diabetic rats: treatment of these animals with insulin partially restored heart rate and plasma catecholamines to control values. It is concluded that hypertension cannot be the cause of the uteroplacental hemodynamic disturbances observed in diabetic rats. Besides, we suggest that bradycardia perhaps, induced by the decreased plasma catecholamines, reflects important myocardial dysfunctions which could contribute to the reduced fetus blood supply and therefore to fetal hypotrophy.