Left atrial type B receptor response during hypothermia in dogs.

1. The response of left atrial type B receptors to hypothermia and its effect on the V-wave pressure-receptor activity relationship was studied in ten anaesthetized and thoracotomized dogs. Hypothermia was produced by surface cooling of the animal. 2. With the drop in the body temperature there was a corresponding fall in the peak frequency of discharge. Reduction in the number of impulses per cardiac cycle and the average resting activity of these receptors became significant only when body temperature fell below 31 degrees C. The Q10 for these receptors is about 2.5, i.e., similar to that for the other mechanoreceptors and consistent with the view that these receptors are in parellel with the muscle fibres. 3. The V-wave pressure-receptor activity relationships were not altered by acute hypothermia.