Catecholamine-induced changes in plasma glucose and insulin levels in the unanesthetized rabbit.

Isoproterenol (ISO) produced dose-related increases in plasma immuno-reactive insulin (IRI) levels in unanesthetized rabbits, whereas epinephrine produced no significant changes. Dose rats of ISO or glucose that produced similar peak increases in glucose levels also produced similar increases in plasma IRI, but the responses to ISO occurred later and were of longer duration than the responses to glucose. Propranolol blocked the increase in plasma IRI produced by ISO, but the ISO-induced rise in plasma glucose was antagonized imcompletely. These data provide supporting evidence for the suggestion that the hyperglycemic activity of ISO in vivo is limited by concurrent ISO-induced changes in peripheral IRI levels.