Da. Pabst et al., THERMOREGULATION OF THE INTRAABDOMINAL TESTES OF THE BOTTLE-NOSED-DOLPHIN (TURSIOPS-TRUNCATUS) DURING EXERCISE, Journal of Experimental Biology, 198(1), 1995, pp. 221-226
Dolphins possess a vascular countercurrent heat exchanger (CCHE) that
functions to cool their intraabdominal testes, Spermatic arteries in t
he posterior abdomen are juxtaposed to veins returning cooled blood fr
om the surfaces of the dorsal fin and tail flukes, In this study, we i
nvestigated the effect of exercise on CCHE function in the bottlenose
dolphin, The CCHE hanks a region of the bowel in the posterior abdomen
and influences colonic temperatures. A rectal probe housing a linear
array of seven copper-constantan thermocouples was designed to measure
colonic temperatures simultaneously at positions anterior to, within
and posterior to the region of the colon flanked by the CCHE, Immediat
ely after vigorous swimming, temperatures at the CCHE decreased relati
ve to resting and pre-swim values: post-swim temperatures at the CCHE
were maximally 0.5 degrees C cooler than pre-swim temperatures. These
data suggest that the CCHE has an increased ability to cool the arteri
al blood supply to the testes when the dolphin is swimming, This abili
ty could offset the increased thermal load on the testes in an exercis
ing dolphin, To the best of our knowledge, this is the first report of
deep body cooling in an exercising mammal that is not undertaking a d
ive,