Researchers find blood pressure sensor in the liver
Berlin – German researchers have identified a completely new target for blood pressure regulation in the liver of mice. In yesterday’s issue of Neuron (69 (2) pp. 332-344) the team headed by Friedrich Luft (MDC Berlin) and Professor Jens Jordan (Hanover Medical School) report that they identified a receptor of osmolality that measures the body's water balance and „feels“ how many molecules are dissolved in a litre of fluid. The blood pressure switch termed TRPV4 is an ion channel within sensory neurons of the liver. In mice it is triggered simply by drinking water. Sudden water intake led to an elevation of blood pressure in mice with the intact TRPV4 channel but not in knock-out mice. Also, in patients with a damaged nervous system, blood pressure readings can rise by as much as 50 mm Hg if the patients drank a half litre of water in one draft, the researchers said. As it seems, each species has a characteristic set point for osmolality, which depends to a great extent on the immediate living conditions. The researchers are now seeking to analyse the processes downstream of the receptor. "The effect of drinking water on blood pressure regulation is already leading to therapeutic consequences in the daily routine of the hospital," Professor Jordan stressed. "We tell patients to drink water who, due to blood pressure regulation disorders, suffer from fainting attacks when standing. This alleviates the symptoms and at the same time we are able to reduce the amount of medication.