Diminished hypotensive response to isoproterenol in streptozotocin-diabetic rats.

1. The cardiovascular reactivity of streptozotocin-diabetic rats has been evaluated with isoproterenol (ISO), a strong beta-adrenergic agonist able to produce, at large dose, myocardial infarction. 2. In the basal state, diabetic rats presented significantly lower heart rate (P less than 0.001), a decreased systolic (P less than 0.05) and an unaltered diastolic blood pressure compared to non-diabetics. 3. Following ISO stimulation, the chronotropic response was similar in both groups of rats, while the fall in systolic and diastolic pressure was markedly reduced compared to those of non-diabetic rats (P less than 0.001). 4. These results suggest that the vasodilation capacity of diabetic rats is diminished.