Maturation and aging-related differences in responsiveness of rat aorta and carotid arteries to α1-adrenoceptor stimulation

Functional correlates of al-adrenoceptors were studied in thoracic aorta and carotid arteries from Wistar rats, at maturation (3- and 8-week-old) and aging (17- and 29-week-old) phases, using phenylephrine (PI-IE) and KCl. PHE and KCI effects on rat aorta did not differ with age. A reduction in maximal contractions to PHE or KCl occurred in carotid arteries during maturation. Concentration-inhibition curves to the alkylating agent chloroethylclonidine or WB4101 suggested at all ages studied a predominance of alpha(1B)-adrenoceptors in aorta. However, alpha(1A)-adrenoceptors may account for some activity in aortas of 29-week-old rats. In carotid arteries alpha(1D)-adrenoceptors account for functional correlates at all ages studied. The results indicate that maturation or aging affects vascular responsiveness or predominant receptor subtype differently in aorta and carotid arteries with intact endothelium.