Variations in the blood pressure of newts according to their respiratory conditions

Abstract

The newt Triturus carnifex is endowed with a mechanism of respiratory compensation which allows the animal to hoard erythrocytes in its spleen and release often large quantities of these into the blood stream, a factor which causes notable variations in all the hematological parameters according to variations in the environmental conditions. The mean arterial pressure, measured at the level of the right aortic arch with a Statham P23 XL transducer, also showed notable variations (from a minimum of about 11 cm to a maximum of about 30 cm of H 2 O). A statistical analysis of these pressure variations showed a positive correlation to blood volume and negative correlation to spleen volume in groups of 8 chlorbutolanaesthetized animals kept at 6°, 12° or 18° C with all their body surface exposed to the air (optimal respiratory condition). In identical groups of animals kept in stagnant water (hypozia-inducing condition), at the same three temperatures, the spleens appeared empty, and both blood volume and pressure showed constant values, intermediate to those of the animals exposed to the air. Thus, the depletion of the spleen in hypoxia is not due to an increase in pressure; however, this factor seems to control the maximum degree of congestion that the spleen can reach in optimal respiratory conditions.