Nicotinic acid adenine dinucleotide phosphate: a new Ca2+ releasing agent in kidney.

Nicotinic acid adenine dinucleotide phosphate (NAADP), a molecule derived from beta-NADP, has been shown to trigger Ca2+ release from intracellular stores of invertebrate eggs and mammalian cell microsomes. NAADP-induced Ca2+ release occurs through a mechanism distinct from that of inositol-1,4,5-trisphosphate- or cyclic ADP-ribose-elicited Ca2+ release. This study investigated whether NAADP can be synthesized in rat kidney. Extracts from glomeruli, mesangial cells, and papilla have high NAADP synthetic capacities. Conversely, synthesis of NAADP in kidney cortex was almost undetectable. Furthermore, 9-cis-retinoic acid significantly up-regulated NAADP synthesis in mesangial cells. Authenticity of NAADP biosynthesis in glomeruli was affirmed by HPLC analysis. NAADP stimulated Ca2+ release from mesangial cell microsomes through a pathway distinct from that of inositol-1,4,5-trisphosphate or cyclic ADP-ribose. NAADP-triggered Ca2+ release may play an important role in regulation of renal function.