The Physiology of the Swimbladder in the Eel Anguilla Vulgaris

Abstract

Abstract S teen , J ohan B. The physiology of the swimbladder of the eel, Anguilla vulgaris . III. The mechanism of gas secretion. Acta physiol. scand. 1963. 59 . 221–241. — The mechanism of gas secretion has been investigated by analysis of blood samples from arteries and veins at both poles of the rete associated with the gas gland. During gas deposition, as measured by gas analyses of the bladder content, the blood is enriched in lactic acid as it circulates in the bladder epithelium. The pH of this blood is about 1 pH unit lower than that in the blood entering the rete from the gills. Part of the lactic acid diffuses from venous to arterial capillaries in the rete . A gradient in gas tension across the rete is produced partly by the existing acid gradient, and partly by the delayed response of the gas tension to the change in acid content which the blood undergoes as it passes the rete . The results strongly support the theory that gas concentration occurs by a counter current multiplication in the rete of a primary gradient induced by the addition of acid electrolytes to the venous blood. The measured values on acid content, pH and blood flow agree very well with the values which have been found adequate, through calculations on the potentialities of such systems, to produce gas pressures higher than those actually measured, and it is concluded that this secretory mechanism will explain secretion of all the atmospheric gases even in deep sea fishes.