Mapks are highly abundant but do not contribute to α1-adrenergic contraction of rat saphenous arteries in the early postnatal period

Abstract

Previously, the abundance of p42/44 and p38 MAPK proteins had been shown to be higher in arteries of 1-to 2-week-old compared to 2-to 3-month-old rats. However, the role of MAPKs in vascular tone regulation in early ontogenesis remains largely unexplored. We tested the hypothesis that the contribution of p42/44 and p38 MAPKs to the contraction of peripheral arteries is higher in the early postnatal period compared to adulthood. Saphenous arteries of 1-to 2-week-old and 2-to 3-month-old rats were studied using wire myography and western blotting. The α1-adrenoceptor agonist methoxamine did not increase the phosphorylation level of p38 MAPK in either 1-to 2-week-old or 2-to 3-month-old rats. Accordingly, inhibition of p38 MAPK did not affect arterial contraction to methoxamine in either age group. Methoxamine increased the phosphorylation level of p42/44 MAPKs in arteries of 2-to 3-month-old and of p44 MAPK in 1-to 2-week-old rats. Inhibition of p42/44 MAPKs reduced methoxamine-induced contractions in arteries of 2-to 3-month-old, but not 1-to 2-week-old rats. Thus, despite a high abundance in arterial tissue, p38 and m do not regulate contraction of the saphenous artery in the early postnatal period. However, p42/44 MAPK activity contributes to arterial contractions in adult rats.