Fall in Hæmatocrit in Sheep after Treatment with Chlorpromazine and Dihydroergotamine

Abstract

IT was recently shown¹ that the jugular hæmatocrit of sheep often fell considerably (by as much as 24 per cent of the initial value, mean = 12 per cent) when the animals were isolated from alarming environmental stimuli, or were subjected to gentle restraint (‘holding’) and soothing for 15–30 min., and that it fell regularly and to an even greater extent (up to 39 per cent of the initial value, mean = 30 per cent) during anæsthesia by pentobarbitonum. Evidence was obtained that these phenomena are a consequence of splenic relaxation, passive filling of the spleen, and segregation therein of an increased fraction of the total red cell mass in a state of dynamic equilibrium with the circulating blood. The remarkable fall in haelig;matocrit after ‘holding’, which we view as emotional or psychological tranquillization leading to diminution of the sympathoadrenal flux from the cerebral cortex, suggested that this might also occur as a result of pharmacological tranquillization by means of ataractic agents.