effect on the blood pressure of normotensive rats than the short chain alkynyl substituent compound wherein n is 5 or less it has also been noted that the long chain compound has less influence on heart rate than the short chain compound the overall results set forth in tables 3 and 4 show that compound 6 n 9 exhibited substantially equal hypotensive effect on shr and nr while compounds 7 n 11 and 8 n 13 acted selectively on shr test 4 effect of the test compounds on the blood pressure in shr and nr eighteen to twenty week old male shr divided into groups of four rats each and eighteen to twenty week old male wistar rats divided into groups of four rats each were orally administered with compound 8 n 13 in the same manner as in test 2 at a dose of 10 mg kg and the blood pressure of each of the rats was measured the results obtained are incorporated in table 5 table 5______________________________________ reduction in blood pressure u03b4 mmhg 1 hr after 2 hrs after administration administration______________________________________shr 41 42wistar rat 16 24______________________________________ as is apparent from table 5 the tendency of compound 8 n 13 to act selectively on shr was also observed in the case of oral administration the acute toxicity of compound 8 n 13 was tested with seven week old male jcl icr mice the physically allowable doses of compound 8 for intraperitoneal administration and oral administration were 800 mg kg and 1 300 mg kg.