Changes in distribution of blood produced by sympathomimetic drugs

Abstract

Changes in the distribution of blood produced by sympathomimetic drugs in cats were followed by measuring changes in the distribution of total body weight. Doses of epinephrine and levarterenol (1 µg/kg) produced initial increases in thoracic weights and decreases in abdominal weights, followed by decreases in thoracic weights and increases in abdominal weights significantly beyond control levels. Doses of 8 µg/kg produced responses approximately twice as large, and significant reductions in hindquarter weights. Responses to isopropylarterenol were of doubtful significance, statistically, and were never biphasic. Infusion of drugs at 0.5 µg/kg min produced responses similar to the first phase of responses to 1 µg/kg. Biphasic responses to single doses of epinephrine and levarterenol were seen after sectioning the vagi and carotid sinus nerves. Carotid artery occlusion produced no changes in weight distribution. Responses to epinephrine at 8 µg/kg were estimated to amount to an increase of 11% in thoracic blood content, and decreases of 12, 7, and 9% in blood contents of the head, abdomen, and hindquarters, respectively.