Role of endogenous hydrogen sulfide on hypoxia‐induced hypothermia in hypertensive rats (LB792)

Role of endogenous hydrogen sulfide on hypoxia‐induced hypothermia in hypertensive rats. Joao Paulo J. Sabino 1 , Renato N. Soriano 1 , Guillermo A. Ariza Traslaviña 2 , Luiz G. S. Branco 1 . 1 Dental School and 2 Medical School of Ribeirão Preto, University of São Paulo. Hypoxia causes a regulated drop in body temperature (Tb) but the mechanisms involved are not completely understood. The role of hydrogen sulfide (H 2 S) a gaseous molecule endogenously produced by cystathionine β ‐synthase (CBS) has been recently documented during hypoxia‐induced hypothermia in normotensive rats. However, no information exists regarding the role of H 2 S during hypoxic hypothermia in spontaneous hypertensive rats (SHR). We then evaluated the effect of the H 2 S donor (Na2S 4 nmol/1µl) and the CBS inhibitor (AOAA 9 nmol/1µl) microinjections into the central nervous system (fourth ventricle) of rats exposed to 10% hypoxia. The Tb was similar in all groups [Saline Wistar group (37.46±0.18 ºC, n= 10), AOAA Wistar group (37.40±0.33 ºC, n= 5), Na2S Wistar group (37.52±0.13 ºC, n= 7), Saline SHR group (37.43±0.43 ºC, n= 8), AOAA SHR group (37.59±0.16 ºC, n= 10) and Na2S SHR group (37.72±0.15 ºC, n= 6)] during basal normoxic condition. Hypoxia induced a typical decrease in Tb in saline injected rats. The decrease in Tb in the Saline SHR group (Δ= ‐1.16±0.11 ºC) was similar to the Saline Wistar group (Δ= ‐0.81±0.20 ºC). In Wistar rats, Na2S administration prevented hypoxia‐induced hypothermia (Δ= ‐0.58±0.16 ºC), whereas AOAA administration significantly increased hypoxia‐induced hypothermia in Wistar rats (Δ= ‐1.60±0.20 ºC), indicating that H 2 S plays a key role on hypoxia‐induced changes in Tb. Surprisingly, neither Na2S (Δ= ‐1.33±0.20 ºC) nor AOAA (Δ= ‐1.61±0.21 ºC) caused any change in hypoxia‐induced hypothermia in SHR. In conclusion, the H 2 S prevents the hypoxia‐induced anapyrexia in normotensive rats, but plays no thermoregulatory role during hypoxia exposition in SHR. Financial support: FAPESP (2011/14779‐4).