Water flux and early signs of entrance into phase 111 of fasting in grey seal pups

• Published in: Acta Physiologica Scandinavica
• Main Authors: NORDØY, E. S., STIJFHOORN, D. E., RÅHEIM, A., BLIX, A. S.
• Format: Article in Journal/Newspaper
• Language: English
• Published: Wiley 1992
• Subjects: Åheim; Arctic; Norway; Tromsø; University of Tromsø
• Online Access: http://dx.doi.org/10.1111/j.1748-1716.1992.tb09324.x; https://api.wiley.com/onlinelibrary/tdm/v1/articles/10.1111%2Fj.1748-1716.1992.tb09324.x; https://onlinelibrary.wiley.com/doi/pdf/10.1111/j.1748-1716.1992.tb09324.x

N orøy , E.S., S tijfhoorn , D.E., R åheim , A. & blix , A.S. 1992. Water flux and early signs of entrance into phase III of fasting in grey seal pups. Acta Physiol Scand 144 , 477482. Received 11 November 1 990 , accepted 13 November 1991 ISSN 0001–677. Department of Arctic Biology and Institute of Medical Biology, University of Tromsø, Tromsø, and Institutt for Energiteknikk, Kjeller, Norway. Body water loss and turnover rate were measured in fasting newly weaned grey seal ( Halichaerus grypus ) pups without access to water for 52 days, by use of bolus injections of deuterated water. Total body water ( N ) was 41.8 ±2.3 (SD)% of total body weight at day 3 and 44.5 ± 5.9 (SD)% at day 51 of fasting ( P > 0.05), while the water content of body core decreased from 73 to 61 yo over the same period. The average water efflux rate in the same period was 362 ± 17 (SD) ml d ‐1 , the reduction in N over the same period contributing 35 yo to this end. The biological half‐time of deuterated water was 38.2 ± 3.3 (SD) d. Plasma osmolality increased from a stable level of 329±11(SD)mosmol kg‐ 1 to 445± 11 (SD) mosmol kg ‐1 after day 38 of fasting. Plasma urea was the major contributor to this increase, in spite of a steadily decreasing urine urea concentration (Nordey et al . 1990) throughout the entire experimental period. It is concluded that grey seal pups endure 52 d of fasting without intake of water with a minor dehydration of body core, while they become hyperosmotic due to increased catabolism of protein after 38 d when sparing of the insulating blubber layer in preparation for life in cold water seems to occur.