Immunoreactive arginine vasopressin in human fetal and neonatal skeletal muscle.

We provide evidence for the presence of arginine vasopressin (AVP) in human fetal and neonatal skeletal muscle using a combination of specific RIA, tangential flow ultrafiltration and reverse-phase HPLC separation. The IR-AVP concentrations are negatively correlated with gestational age (r = -0.75, P less than 0.0001) and range from 1 to 10 pmol/g wet wt at 15 weeks gestation to 0.04 pmol/g wet wt at term. This IR-AVP substance is of low molecular weight (less than 3000 mol. wt), elutes in the same position as standard AVP after HPLC separation and is detected by four different anti-AVP antisera.