Compensatory effects of nitric oxide and hydrogen sulfide in thoracic aorta in conditions of essential hypertension.

Several studies have already confirmed the cross-talk between nitric oxide (NO) and hydrogen sulfide (H2S) signaling systems in normotensive rats, but results in spontaneously hypertensive rats (SHRs) are limited. The aim of this study was to describe the vasoactive effects of endogenous NO and exogenous Na2S and their interaction in vasomotor responses of the thoracic aorta (TA) in young (4 weeks old) and adult (16 weeks old) normotensive Wistar rats and SHRs. Although hypertrophy of the heart was observed in young and adult SHRs, the sBP was increased only in adulthood. The contractile responses of the TA were decreased in young as in adult SHRs with the key participation of the endogenous NO/NO-synthase system. NO-dependent component of acetylcholine-induced relaxation was higher in the young SHRs and comparable in the adult SHRs. NOS activity was higher in the young SHRs as well as in the adult SHRs. The acute NO inhibition generally increased the relaxant phase of H2S donor responses; nevertheless, the development of hypertension potentiated this effect. The TA of the SHRs is endowed with a unique inherent predisposition of vasoactive mechanisms, which serve as compensatory processes during the developed stage of hypertension: the NO component and H2S signaling pathways are implicated. [ABSTRACT FROM AUTHOR]

Interakciu medzi signálnymi dráhami oxidu dusnatého (NO) a sírovodíka (H2S) už potvrdili viaceré štúdie u normotenzných potkanov, avšak výsledky u spontánne hypertenzných potkanov (SHR) sú limitované. Cieľom štúdie bolo charakterizovať vazoaktívne účinky endogénneho NO a exogénneho H2S a ich interakciu vo vazomotorických odpovediach hrudníkovej aorty (HA) u mladých (4-týždňových) a dospelých (16-týždňových) normotenzných Wistar potkanov a SHR. Hoci hypertrofia srdca sa pozorovala tak u mladých, ako aj dospelých SHR, hypertenzia bola zaznamenaná len u dospelých SHR. Kontraktilné odpovede HA boli zmenšené tak u mladých, ako aj u dospelých SHR, s výrazným podielom endogénneho NO systému. NO-závislá zložka acetylcholínom vyvolanej relaxácie bola väčšia u mladých a porovnateľná u dospelých SHR. Aktivita NO-syntázy bola zvýšená u obidvoch vekových skupín SHR. Akútna endogénna inhibícia NO všeobecne zvýšila relaxačnú fázu odpovedí H2S donora, avšak rozvoj hypertenzie tento efekt ešte potencioval. Hrudníková aorta SHR je vybavená vrodenou predispozíciou vazoaktívnych mechanizmov zahŕňajúcich tak NO, ako aj H2S signálnu dráhu, ktoré slúžia ako kompenzačné v štádiu rozvinutej hypertenzie. [ABSTRACT FROM AUTHOR]