Cloacal and salt-gland ion excretion in the seagull, Larus glaucescens, acclimated to increasing concentrations of sea water

High dietary sodium chloride and body temperature in the domestic fowl and the glaucous-winged gull

Arad and Skadhauge (1986) correlated plasma sodium to calcium ratio and body temperature in domestic fowl (Gallus domesticus) during increased dietary sodium chloride intake which increased plasma sodium concentration. During acclimation to high dietary NaCl, body temperature should increase in proportion to the increase in plasma sodium concentration, and body temperature should increase less in gulls than in chickens because salt gland secretion of NaCl by gulls should prevent elevation of plasma sodium concentration. Plasma osmolality, plasma sodium concentration, plasma concentrations of total calcium and ionized calcium, and body temperature and panting threshold were measured in domestic roosters and Glaucous-winged gulls before and after exposure to high NaCl diets. Gull body temperature (40.4 +/- 0.2 degrees C) increased significantly (P < 0.05) during salt acclimation. Rooster body temperature (41.0 +/- 0.2 degrees C) did not increase significantly. Plasma sodium concentration increased in gulls (5.4 +/- 0.5%, P < 0.01) and was correlated with body temperature (r = 0.497, P < 0.05); the 3.8 +/- 1.0% increase in plasma sodium concentration in roosters (P < 0.01) was not, suggesting that change in body temperature might be a response to the magnitude of increase in plasma sodium concentration. Plasma ionized calcium concentration increased by 12.9 +/- 4.6% (P < 0.01) in gulls and by 5.3 +/- 1.0% (P < 0.01) in roosters. Plasma sodium concentration was correlated with calcium ion concentration in both gulls (r = 0.635, P < 0.05) and roosters (r = 0.664, P < 0.05). In neither species were ratios of sodium to total calcium plasma concentration or sodium to ionized calcium concentration altered or related to body temperature.(ABSTRACT TRUNCATED AT 250 WORDS)

Plasma arginine vasotocin and angiotensin II in the water deprived Kelp gull (Larus dominicanus), Cape gannet (Sula capensis) and Jackass penguin (Spheniscus demersus)

1. The basal levels of the osmoregulatory hormones, arginine vasotocin (AVT) and angiotensin II (AII) were measured (by radioimmunoassay) in the plasma of conscious Kelp gulls, Cape gannets and Jackass penguins. 2. The responses of the hormones to similar degrees of hypertonicity and hypovolemia caused by water deprivation have also been determined. 3. Dehydration elevated plasma AVT and plasma AII in all three species. 4. The AVT concentration was increased by 2-4 fold and although in each case the correlation between plasma osmolality and plasma AVT was highly significant (2P less than 0.01), the sensitivity of release was greater in the gull (1.13 pg/ml per mOsm/kg) than in the gannet (0.36 pg/ml per mOsm/kg) or penguin (0.44 pg/ml per mOsm/kg). 5. Dehydration increased plasma AII 3-fold in the three bird types.