Effect of hydrogen sulfide (H2S) in the commissural NTS on the ventilatory and hemodynamic response to hypoxia and hypercapnia in normotensive and hypertensive animals

Abstract

Hypertension is a public health problem that affects a large portion of world population that in most cases don`t know that they have the disease. Hypertension has similarities with essential hypertension observed in Spontaneous Hypertensive Rats (SHR). Among the central regions involved with the increased sympathetic activity and blood pressure in SHR is commissural NTS (cNTS), which receives baroreceptor and chemoreceptor afferents and where the presence of the enzyme cystathionine beta-synthase (CBS) has been documented. This enzyme endogenously forms H2S which has been reported as the third member of the gaseous neurotransmitter, after nitric oxide (NO) and carbon monoxide (CO). No reports exist about the role of H2S in the cNTS, and its relationship with cardiovascular and respiratory responses to hypoxia and hypercapnia in hypertensive and normotensive animals. Therefore, we aim to shed light into the neurochemical control of cardiovascular and respiratory systems, assessing the putative participation of H2S in the cNTS, mediating physiological responses to hypoxia and hypercapnia of normo- and hypertensive rats. For this purpose will be run four experimental protocols, assessing: 1) the effects of micro-injections in the NTS, the CBS inhibitor (AOAA) and donor of H2S (Na2S) in pulmonary ventilation, blood pressure and heart rate during normocapnia and normoxia; 2) the effects of micro-injections in the NTS, the inhibitor CBS (AOAA) and donor of H2S (Na2S) in pulmonary ventilation, blood pressure and heart rate in response to hypercapnia; 3) the effects of micro-injections in the NTS, the inhibitor of the enzyme CBS (AOAA) and donor of H2S (Na2S) in pulmonary ventilation, blood pressure and heart rate in response to hypoxia, and 4) the comparative analysis of the expression of the enzyme CBS the cNTS between hypertensive and normotensive animals. (AU)