A study of gastric stretch receptors. Their role in the peripheral mechanism of satiation of hunger and thirst

A number of investigators have shown that reflex respiratory, pupillary or vascular effects are produced by stimulating the central end of the vagi below the diaphragm (Brodie & Russell, 1900; Neumann, 1914; Carlson & Luckhardt, 1921; Harper, McSwiney & Suffolk, 1935), although these observations do not indicate that nerve fibres of the stomach are involved. However, Irving, McSwiney & Suffolk (1937) have shown clearly from a study of pupillary responses that sensory impulses in the vagus are produced when the stomach is distended. The presence of myelinated afferent fibres in the vagus at the level of the diaphragm was pointed out by Edgeworth (1892) and confirmed by Langley (1892). Evidence for spindle-shaped endings in the stomach has been provided by the histological studies of Langworthy & Ortega (1943) who showed that they are connected to myelinated fibres thought to be sensory in function. In spite of these studies, impulses from afferent fibres of the stomach have been recorded only recently (Paintal, 1953c). These were in fact found in the course of an investigation into the normal function of receptors stimulated by phenyl diguanide (Paintal, 1954a). Since then these gastric stretch receptors have been studied further, and several interesting facts regarding their responses to mechanical stimuli and drugs have emerged. Their responses to drugs are described in another paper (Paintal, 1954b). Recent studies (Janowitz & Grossman, 1949; Share, Martyniuk & Grossman, 1952) have shown conclusively that food intake in dogs is influenced to a large extent by distension of the stomach whether the distension is achieved mechanically by a balloon or by calorically inert food. Further, distension of the stomach with a water-filled balloon inhibits sham drinking, a reflex that is * Present address: Vallabhbhai Patel Chest Institute, University of Delhi, Delhi, India. 17 PHYSIO. CXXVI