THE EFFECT OF HEATING THE SCROTUM OF THE RAM ON RESPIRATION AND BODY TEMPERATURE

¹ C.S.I.R.O., Division of Animal Physiology, The Ian Clunies Ross Animal Research Laboratory, Prospect, N.S.W., Australia

At ambient temperatures of 18 ± 2° C., heating the scrotumn of the fullyfleeced ram to above 36° C. evoked a polypna which immediately stopped when the scrotum was cooled again. Only small increases of respiratory rate occurred when an identical area of flank skin was similarly heated. The responses to heating the scrotum started before intra-carotid temperatures changed and were maintained despite falls in deep body temperature of up to 2·2° C. Deneirvation of the scrotum abolished the reflex. When rams were shorn and flank skin temperatures were in the range 30·0-34·3° C., the rams no longer panted when the scrotum was heated. A second, unidentified channel of heat loss was then evoked and body temperature again fell.

Note:

I wish to thank Mr. J. K. Voglmayr for skilled assistance throughout and Dr. B. P. Setchell of the Veterinary Research Station, Glenfield, N.S.W. for help during the experiments with implanted thermocouples. I am grateful to Dr. J. Bligh of the A.R.C. Institute of Animal Physiology, Babraham, and to my colleagues, Messrs. A. H. Brook and J. C. D. Hutchinson for valuable discussion.