Effects of arg8-vasopressin on developing skeletal muscle

Arg8-vasopressin (AVP), a nonapeptide produced by neuroendocrine cells of the hypothalamus and released into the blood stream at the level of the·neurohypophysis, exerts i!s multiple physiological actions through two types of receptors: the V1 receptor (liver, smooth muscle cells) coupled to phosphoinositidase c, and the V 2 receptor (kidney), coupled to adenylate cydase. Very little information is available about biologic::al actions of AVP on skeletal muscle. We have recently reported that AVP induces significant responses in skeletal myogenic cells in culture, consisting in stimulation of phosp4oinositide (PI) turnover, with rapid (3-5 s") production of inositol 1•4-5 trisphosphate, and modifications of intracellular calcium concentration and pH. The response to AVP seems to be regulated by protein kinase C (PKC), a key enzyme in myogenic differentiation, as shown by the modifications induced by TPA, and their reversion by the PKC inhibitor staurosporine.