ANP is secreted by the hea. Endocrine/Paracrine functions of the kidney: Substance Site of secretion Renin Granular cells or juxtaglomerular cells (JG cells) of the juxtaglomerular apparatus (JGA) Erythropoetin Interstitial cells in the peritubular capillary bed Prostaglandin E2 (PGE2) Renal medullary interstitial cells (RMICs), macula densa, and by cells of collecting duct 1,25- Dihydroxycholecalciferol (Calcitriol or Vitamin D3) Cells of proximal tubules of the kidneys PGI2 and other prostaglandins Aerioles and glomeruli Ref: Ganong&;s Review of Medical Physiology 26th edition Pgno: 662