Plasma Insulin Concentrations During Infusion of Potassium and Sodium Chloride Solutions Into Conscious Splenectomized Sheep

Abstract

Haematocrit values, plasma osmolality and the plasma concentrations of sodium, potassium, chloride and insulin were measured in carotid arterial blood before, during and after intravenous infusion of NaCI (0· 5 moll-i) and KCI (0· 5 moll-i) at 2 ml min~l for 105 min into six conscious splenectomized sheep. Hypertonic NaCI infusion was associated with a fall in haematocrit of 1 ·30 ± 0·10 % (P < 0·001) and no consistent change in plasma insulin concentration occurred during this infusion. Hypertonic KCI infusion caused the haematocrit to increase by 1·70 ± 0·39 % (P < 0·001) and the plasma insulin concentration to increase by 60·0± 16·3 jlU ml-1 (P < 0·01). It was concluded that this increase in insulin concentration was caused by elevation of the plasma potassium concentration and was not due to coincident increases in plasma chloride concentration or osmolality. Shrinkage of the extracellular fluid volume during KCI infusion made no major contribution to the increase in insulin concentration which was probably the result of increased release from the pancreas. [Other keywords: hyperkalaemia, hypernatraemia.j