Contractility and endothelium-dependent relaxation of resistance vessels in polycystic kidney disease rats

Hypertension and vascular disease are common complications in autosomal-dom inant polycystic kidney disease (ADPKD). The role of changes in morphology and reactivity of resistance vessels in this disease have not previously be en studied. Mesenteric resistance arteries were dissected from 8- to 14-wee k-old heterozygous Han:SPRD polycystic kidney disease (PKD) rats, homozygou s normal Han:SPRD littermates (HSPRD) and Sprague-Dawley rats (SD). The mor phology, noradrenaline (NA) contractility, endothelium-dependent acetylchol ine (ACh) relaxation before and after incubation with L-G-nitro-L-arginine methyl ester (L-NAME), and endothelium-independent 3-morphollino-sydnonimin e (SIN-1) relaxation were studied with the Mulvany-Halpern myograph. Blood pressure and morphology of vessels were the same in all groups of rats, apa rt from a slightly higher media/lumen ratio in heterozygous PKD rats (p < 0 .05). Active wall tension and contractile sensitivity to NA were higher in both heterozygous PKD rats and HSPRD than SD rats (p < 0.05). The maximum e ndothelium-dependent relaxation rate was markedly decreased in heterozygous PKD (19 +/- 9%) and HSPRD (34 +/- 12%) compared to SD rats (75 +/- 11%) (p < 0.05). After incubation with L-NAME, ACh-induced relaxation was signific antly attenuated in SD rats, less attenuated in HSPRD, and not significantl y changed in heterozygous PKD rats. SIN-1-induced endothelium-independent r elaxation was similar in all three groups. In conclusion, hyperreactivity t o NA and impaired endothelium-dependent relaxation were present in resistan ce vessels from Han:SPRD rats, especially in animals with PKD. These abnorm alities in resistance vessels from PKD rats may be important for the develo pment of hypertension and vascular disease. Copyright(C) 1994 S. Karger AG. Basel.