Relaxant and contractile responses to prostaglandins in premature, newborn and adult baboon cerebral arteries.

Dose-dependent actions of prostaglandins (PGs) were investigated on cerebral arterial strips isolated from premature, newborn and adult baboons. PGE1 an PGE2 in low concentrations (10(-9) to 10(-7) M) elicited significant relaxation in both premature and newborn baboon cerebral arteries. Arteries from adult baboons showed slight or small relaxation in response to these PGs. PGE1 and PGE2 in higher concentrations (10(-8) to 10(-6) M) caused no contraction in premature and newborn arteries, but significant contraction in adult arteries. PGF2 alpha (10(-9) to 10(-7) M) elicited relaxations in arteries from baboons of every age group, being greater in prematures and newborns than in adults. PGF2 alpha (3 X 10(-7) to 10(-5) M) produced a slight or small contraction in prematures and newborns, respectively, whereas larger contraction was induced in the adult artery. PGI2 (prostacyclin) (10(-8) to 10(-6) M) produced dose-dependent relaxation in arteries from baboons of all age groups with no significant difference in the relaxant effect among the three age groups. Effective concentration (EC25) values for relaxant effect of PGE1 and PGE2 were much less than those of PGF2 alpha and PGI2 in premature and newborn arteries. In adult cerebral arteries, only PGF2 alpha and PGI2 were effective in causing a significant relaxation. In premature and newborn arteries, PGE1 and PGE2 were not effective in causing a significant contraction, whereas in adult arteries EC25 values for contractile effects of PGE1 and PGE2 were less than those for PGF2 alpha.(ABSTRACT TRUNCATED AT 250 WORDS)