Oxygen consumption in the rectal gland of the dogfishScyliorhinus canicula and the effects of cyclic AMP

Oxygen consumption was measured in slices of dogfish (Scyliorhinus canicula) rectal gland tissue and compared with spleen and kidney. Concentrations of dibutyryl cAMP and theophylline that have previously been shown to stimulate secretion from the perfused gland and to produce a large increase in ouabain binding in this tissue, greatly increased oxygen consumption in the rectal gland but were without effect on oxygen consumption in the spleen and the kidney. Addition of theophylline alone increased rectal gland oxygen consumption and no further increase was detected on addition of cAMP at the concentration used (0.05 mmol l−1). Ouabain (10−4 M) significantly decreased oxygen consumption in all three tissues studied and completely abolished the increase in oxygen consumption of the rectal gland produced as a result of the addition of cAMP and theophylline. These findings are discussed in relation to the apparent specific effect of cAMP on the rectal gland and its possible mode of action in this tissue.