Effect of Acute and Antecedent Hypoglycemia on Sympathetic Neural Activity and Catecholamine Responsiveness in Normal Rats

Adrenergic responsiveness to acute hypoglycemia is impaired after prior episodes of hypoglycemia. Although circulating epinephrine responses are blunted, associ-ated alterations in adrenal sympathetic nerve activity (SNA) have not been reported. We examined adrenal nerve traffic in normal conscious rats exposed to acute insulin-induced hypoglycemia compared with insulin with (clamped) euglycemia. We also examined adrenal SNA and catecholamine responses to insulin-induced hypoglycemia in normal conscious rats after two ante-cedent episodes of hypoglycemia (days 22 and 21) compared with prior episodes of sham treatment. Acute insulin-induced hypoglycemia increased adrenal sympa-thetic nerve traffic compared with insulin administra-tion with clamped euglycemia (165 6 12 vs. 118 6 2