Cessation of renal function during diving in the trained seal (Phoca vitulina)

✍ Scribed by Murdaugh, H. V. ;Schmidt-Nielsen, Bodil ;Wood, J. W. ;Mitchell, W. L.

• Publisher: Wiley (John Wiley & Sons)
• Year: 1961
• Tongue: English
• Weight: 371 KB
• Volume: 58
• Category: Article
• ISSN: 0095-9898
• DOI: 10.1002/jcp.1030580307

✦ Synopsis

The adaptive response of the seal to diving appears composed of two changes, a reflex bradycardia with resultant decrease in cardiac output reported by Scholander ('40), and an arterial constrictor response with cessation of blood flow through muscle beds described by Irving, Scholander, and Grinnell ('41 ). These changes allow the seal to maintain a higher oxygen saturation of blood perfusing the brain for a longer period of time. Scholander ('40) thought this response was of a reflex nature because bradycardia may appear within one heart beat of submersion.

Bradycardia of diving has been experimentally produced by different techniques. Scholander ('40) studied trained seals dived on a teeter board, but Lowrence, Nickel, Smythe and Bradley ('56) obstructed respiration by placing an occluded cone over the seal's nose to obtain bradycardia. The electrocardiograms during these two conditions differ. The accustomed dive of the trained seal on the teeter board resulted in a bradycardia without arrythmias (Scholander, '40), but respiratory obstruction resulted in bradycardia of lesser degree but accompanied by T wave inversion and arrythmias (Lowrence, Nickel, Smythe and Bradley, '56). Electrocardiograms taken on the free swimming seal (Murdaugh, Seabury and Mitchell, '61) were like the electrocardiograms taken by Scholander using teeter board diving.

Bradley and Bing ('42), using the occluded nose cone technique and forced submersion in the untrained seal reported decreases in rates of urine flow and glomerular filtration in the seal. In our pre-