Mechanism of tolerance to renal ischemia in harbor seal: role of membranes.
Many diving animals are capable of engaging in long breath-hold dives. Investigations were undertaken to compare the active tubular transport of organic ions between kidney slices from harbor seals (Phoca vitulina) and rats (control) under anoxia or low pH or both. Para-aminohippurate (PAH) and tetraethylammonium (TEA) were used as a representative organic anion and cation, respectively. The slice-to-medium concentration ratios (S:M) of PAH (congruent to 2.5) in the harbor seal was not altered (unlike in the rat) after 60 min of incubation in a nitrogen atmosphere but was reduced to congruent to 1.0 in the presence of 10(-4) M 2,4-dinitrophenol. Subsequent studies also demonstrated that PAH uptake in the harbor seal was not influenced by pH of the incubation medium over a range of 6.0 to 7.4. In contrast, PAH uptake was very sensitive to the medium pH in the rat, decreasing significantly with reduction in pH. Although the TEA uptake decreased in anoxia in both species, it decreased considerably less in the harbor seal than in the rat (40 vs. 70%). However, TEA uptake decreased significantly at low pH in both species. The magnitudes of increase in intracellular Na and of decrease in intracellular K in anoxia were consistently less in the harbor seal than in the rat, especially at low pH. On the basis of these and other findings reported in the literature, cellular mechanisms for the remarkable ischemic tolerance of the seal kidney are discussed.
Hong
S K
SK
Department of Physiology, State University of New York, Buffalo 14214.
D000818:Animals; D001692:Biological Transport / Q000502:physiology; D010872:Caniformia / Q000502:physiology*; D004242:Diving; D006863:Hydrogen-Ion Concentration; D000860:Hypoxia / Q000378:metabolism / Q000662:veterinary; D007511:Ischemia / Q000378:metabolism / Q000662:veterinary*; D007668:Kidney / Q000098:blood supply / Q000378:metabolism*; D046048:Seals, Earless / Q000502:physiology*; D000254:Sodium-Potassium-Exchanging ATPase / Q000378:metabolism
D000254:Sodium-Potassium-Exchanging ATPase