Functional evidence of alpha(1D)-adrenoceptors in the vasculature of youngand adult spontaneously hypertensive rats

The role of alpha(1D)-adrenoceptors in the vasculature of spontaneously hyp ertensive (SHR) and normotensive Wistar Kyoto rats (WKY), of different ages was assessed in pithed rats by the use of the selective alpha(1D)-adrenoce ptor antagonist BMY 7378 (8-[2-[4-(2-methoxyphenyl)-1-piperazinyl]ethyl]-8- azaspiro [4.5]decane-7,9-dione dihydrochloride). BMY 7378 displaced the pre sser effect of phenylephrine in young pre-hypertensive pithed SHR rats, but produced no effect in young WKY rats (dose ratio of 3.4 and 1.6, respectiv ely), while in adult rats BMY 7378 produced a greater shift in the phenylep hrine response curve than in younger animals (dose ratio of 3.2 and 6.2 in WKY and SHR, respectively). The presence of alpha(1D)-adrenoceptors in the vasculature of pre-hypertensive rats, suggests its role in the pathogenesis /maintenance of increased blood pressure.