BINDING-SITES FOR ATRIAL-NATRIURETIC-PEPTIDE (ANP) ON CULTURED PITUICYTES - LACK OF EFFECT OF ANP ON RELEASE OF NEUROHYPOPHYSEAL HORMONES INVITRO

Receptors for atrial natriuretic peptide (ANP) are known to be present in the posterior pitutary gland and this is a possible site of action of ANP to modulate neurohypophysial hormone release. Pituicytes cultured from adult rat neurohypophyses are show to possess high affinity binding sites for ANP, suggesting that in vivo a population of the neurohypophysial ANP receptors are present on these astrocytic glial cells. Alpha-rANP (1-100 nM) did not modulate the basal or electrically stimulated release of oxytocin or vasopressin from the isolated neurohypophysis in vitro. The physiological significance of the glial ANP binding sites thus remains unknown.