Exogenous hydrogen sulfide produces hemodynamic effects by triggering central neuroregulatory mechanisms

Recently, it was found that hydrogen sulfide (H2S) may serve as an important transmitter in peripheral organs as well as in the brain. The aim of the present study was to evaluate the possible function of H2S in the brain regulation of the circulatory system. Experiments were performed on conscious, male, Wistar-Kyoto rats. Mean arterial blood pressure (MABP) and heart rate (HR) were recorded continuously under baseline conditions and during infusions into the lateral cerebral ventricle (LCV) of the experimental animals. In control series LCV infusion of vehicle (Krebs-Henseleit bicarbonate-buffer) did not cause significant changes in MABP or HR. LCV infusion of H2S donor (NaHS) at the rate of 400 n/h resulted in an increase in MABP, whereas infusions at the rate of 100 n/h and 200 n/h failed to change MABP. On the other hand LCV infusion of H2S donor at the rate of 200 n/h caused a significant increase in HR while infusion at the rate of 400 n/h produced an increase in HR, which was smaller than this observed during infusion at the rate of 200 n/h. H2S donor administered at the rate of 100 n/h failed to affect HR. In conclusion, the present study demonstrates that exogenous hydrogen sulfide changes hemodynamic parameters by centrally mediated mechanisms. The hemodynamic effect seems to be dependent on H2S concentration in cerebrospinal fluid. It appears that the hypertensive response may occur at a concentration, which does not exceed twice the physiological level.