Respiration of avian salt-secreting gland in tissue slice experiments

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Abstract
Oxygen consumption was determined in tissue slices of the salt gland of the herring gull (Larus argentatus). The oxygen consumption of slices in a Krebs phosphate medium was 10.0 µl O2/mg tissue dry wt. hr. The addition of metacholine, which simulates the normal parasympathetic stimulation of the gland in vivo, caused an increase in rate of respiration of almost 50%. Doubling the NaCl concentration in the medium inhibited respiration. The presence of metabolic substrates, in particular of succinate, greatly augmented respiration. Lithium ion, which has little effect on tissue respiration in general, stimulated the oxygen consumption of salt gland slices. Potassium, which stimulates respiration in most other tissues, had a pronounced inhibitory effect on salt gland slices. A comparison of the observed oxygen consumption of slices with the calculated energy requirement for sodium transport at rates common in the living bird shows that the in vivo respiration must be much higher than that observed in slices. If the gland in vivo derives the required energy from aerobic respiration it must be characterized by a high rate of oxygen consumption and a very high rate of blood flow.