H<sub>2</sub>S-Mediated Dilation of Pial Arteries in Rats of Different Ages: Contribution of K<sub>ATP </sub>and BK<sub>Ca</sub>-Channels

Abstract

Reactions of pial arteries to exogenous hydrogen sulfide exposure and assessment of the contribution of KATP and BKCa-channels to H2S-mediated dilation was studied in rats of different ages. Intravital microphotography in Sprague-Dawley rats aged 4 and 18 months was used to study the reactions of pial arteries of various diameters to the exposure of exogenous hydrogen sulfide donor solution – sodium hydrosulfide (NaHS, 30 μM), as well as their change with the preliminary use of potassium channel blockers: KATP (glibenclamide, 10 μM) and BKCa (tetraethyl ammonium, 2 mM). It was found that inhibition of H2S-mediated dilation of pial arteries and increase in constrictor responses to exogenous hydrogen sulfide exposure are taking place in rats with age. Age-related changes in H2S-induced dilatory response of the pial arteries in rats depend on the size of the vessels. With age, there is a decrease in the number of dilations of pial arteries with a diameter of more than 20 μm. At the same time, aging does not affect the dilatation of smaller arteries. These disorders are probably associated with changes in the processes caused by the activation of potassium channels. It was found that aging is accompanied by the increasing of KATP-channels contribution to the implementation of H2S-mediated dilation in pial arteries with diameters less than 40 μm. BKCa-channels contribution to the dilatation decreases with age. In 18 months, rats, these channels barely participate in H2S-mediated dilation in arteries with diameters more than 20 μm.