Acute hyperglycemia and hyperinsulinemia enhance adrenergic vasoconstriction and decrease calcitonin gene-related...

Area of Science:

• Cardiovascular Physiology
• Endocrinology
• Neuroscience

Background:

• Transient hyperglycemia and hyperinsulinemia are linked to hypertension development.
• Understanding their impact on vascular tone control is crucial.

Purpose of the Study:

• To investigate the effects of acute hyperglycemia and/or hyperinsulinemia on neuronal and humoral control of vascular tone in rats.
• To determine the specific roles of glucose and insulin in altering vascular responses.

Main Methods:

• Rats were anesthetized and pithed, with arterial blood pressure monitored.
• Vascular responses to spinal cord stimulation and vasoactive agents were assessed during glucose or insulin infusions.
• Specific interventions isolated the effects of hyperglycemia versus hyperinsulinemia.

Main Results:

• Glucose infusion (hyperglycemia and hyperinsulinemia) augmented adrenergic nerve-mediated pressor responses and attenuated calcitonin gene-related peptide (CGRP)-mediated depressor responses.
• Hyperglycemia alone (without hyperinsulinemia) primarily augmented adrenergic pressor responses.
• Hyperinsulinemia with euglycemia also augmented adrenergic pressor responses and attenuated CGRP depressor responses.

Conclusions:

• Acute hyperglycemia and hyperinsulinemia enhance adrenergic vasoconstriction and impair CGRP-mediated vasodilation.
• Increased plasma insulin concentration, associated with hyperglycemia, appears to be the primary driver of altered neuronal vascular regulation.
• These findings suggest a mechanism linking metabolic disturbances to hypertension via neurovascular dysfunction.