engleski

Vascular responses in cerebral resistance arteries in female Dahl S, Consomic SS-13BN and Brown Norway ratg strains

Consomic SS-13BN rats are derived by transferring chromosome 13 containing the renin gene from the Brown Norway (BN) normotensive rat strain into the Dahl S genetic background. In contrast to Dahl S rats, SS-13BN rats exhibit normal regulation of the renin -angiotensin system (RAS) during changes in salt intake. The goal of this study was to determine whether responses to vasodilator stimuli that are lost in female Dahl S rats are restored in SS-13BN rats. Responses to acetylcholine (ACh), hypoxia (PO2 reduction to 40-45 mm Hg) and iloprost (stable PGI2 analog) were assessed in isolated middle cerebral arteries (MCA) of female Dahl S, SS-13BN , and BN rats on a low salt (0.4% NaCl) diet. MCA of Dahl S rats dilated in response to ACh and exhibited a paradoxical constriction in response to hypoxia and iloprost. Dilator responses to hypoxia (but not iloprost) were restored and dilation to ACh was significantly increased in the SS-13BN MCA. MCA from the female BN rats dilated in response to ACh and iloprost, but failed to dilate in response to reduced PO2. MCA of Dahl S and SS-13BN rats exhibited an impaired myogenic response as compared to the MCA of BN rats. Resting (physiological salt solution) and maximum (Ca++ free solution) diameters of the MCA of the SS and SS-13BN were significantly less than the diameters of the BN MCA. These results suggest that the restoration of the normal regulation of the RAS enhances vasodilator responses to ACh and hypoxia in female SS-13BN consomic rats. But substitution of BN chromosome 13 does not alter the ability of the SS MCA to respond to increased intravascular pressure.

cerebral arteries; renin-angiotensin system; female; acetylcholine

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