Factors Determining the Course of the Gastric Secretion in Elasmobranchs

Abstract

The continuous secretion of very small amounts of highly acid gastric juice in fasting skates (Raja diaphanes or R. erinacea) is unaffected by section of the vagi, injection of large doses of atropine, or subcutaneous introduction of histamine, but is inhibited for several hours by adrenaline or (to a less marked degree) by stimulation of the sympathetic. Destruction of the spinal cord (cervical region to tail) results in a "paralytic" secretion of gastric juice (sympathetic influence eliminated), commencing after 1 day and continuing up to even 16 days, with volume up to 30 cc. per day, pH from 2.0 to 5.0, and digestive power moderate. The freezing point depression of the juice becomes progressively lower (Cl concentration unaltered), as also that of the blood. Secretion considered as very probably the result of vascular changes in the viscera due to disconnection of peripheral and central parts of the sympathetic.