ROLE OF HEPATIC RECEPTORS IN CONTROLLING BODY-FLUID HOMEOSTASIS

Haberich and co-workers [1,2] were the first to suggest the existence of osmoreceptors in the hepatoportal region. In their studies, they sh owed that infusion of water into the hepatic portal vein produced a ra pid increase in urine flow, whereas similar infusion into the vena cav a had no significant effect. Electrophysiological studies by Andrews a nd Palmer [3] and Niijima [4] provided further evidence for the existe nce of baroreceptors and osmoreceptors in this region. These authors r ecorded pressure- and osmolality-sensitive afferent discharges from th e hepatic nerves, an indication that the mammalian liver is not only a metabolic, clearance, or storage organ but also contains many recepto rs, now shown to include osmoreceptors, ionic receptors and barorecept ors [5, 6]. Given the role of such receptors in the systemic circulati on, it is possible that they may also be involved in the regulation of body fluid homeostasis in the hepatic circulation. A growing body of evidence suggests that neural receptors within the liver and its vascu lature detect a variety of physiological events and are responsible fo r the activation of a number of physiological responses, which may pla y an important role in regulating body fluid homeostasis. In fact, the clinical course of patients with liver disease is frequently complica ted by abnormalities in body fluid homeostasis, such as ascites and pe ripheral edema. In this paper, we review the literature concerning the role of the liver in body fluid homeostasis control.