Cutaneous microcirculatory responses to insulin administration in the fasted and hexamethonium-treated rabbit, with special regard to peripheral circulating leukocytes (original) (raw)

1975, Microvascular Research

Cutaneous microcirculatory responses to insulin administration (0.5, I .O, and 2.0 IU/kg, iv) were studied in a transparent chamber installed in a rabbit ear under fasting conditions. Vital microscopic observations were made visually with photomicrography and microphotoelectric plethysmography. Following the insulin administration, a marked and persistent vasoconstriction and a low-flow state were developed invariably in connection with insulin hypoglycemia. During the low-flow state, leukocytes became highly adherent especially in venules; in arterioles they obstructed the flow of erythrocytes into the distal vessels, and consequently a profound microcirculatory hypohematocrit-hypoperfusion state occurred. Leukocytes adhering to venules were not easily washed away even by the rapid blood flow, however, they never formed aggregates, thrombi, or coagulates. Administration of glucose (1 .O g/kg, iv) during the insulin-induced low-flow state (1.5 hr after insulin, 2.0 IU/kg iv), which could relieve, if any, insulin convulsions, resulted in a transient complete arrest of the microcirculation followed by a moderated recovery of it. In addition, peripheral circulating leukocytes were counted and a significantly reduced count of lymphocytes was obtained after the insulin administration. Some implications of the findings are discussed from the point of view of hematology as well as physiology.