Aim: 

It is widely assumed that nucleotides are released as autocrine or paracrine agents to act on P2X and P2Y receptors on renal tubular epithelium to regulate solute and water transport. P2 receptors (P2Rs) have been indentified on both apical and basolateral membranes of tubular epithelial cells throughout the nephron. The purinoceptors inhibit (apical membrane) or stimulate (basolateral membrane) sodium reabsorption and inhibit water reabsorption (Unwin RJ et al, News Physiol Sci, 18:237-41, 2003). Our group demonstrated that guanosine 5'-triphosphate (GTP) is able to enhance the differentiation of different cell line ( Pietrangelo et al, J Physiol, 572:721-33, 2006; Guarnieri et al, Int J Dev Neurosci 27(2):135-47, 2009).

Methods and Results: 

We investigated whether GTP has a role in cortical collecting duct cell line (M1-CCD) of the renal system.Calcium imaging experiments revealed an increased [Ca2+]i with both an oscillatory and transient kinetic of M1-CCD cells tested stimulated with extracellular 500 mM GTP. Cellular proliferation assay demonstrated that 500 mM GTP-stimulated M1-CCD cells has a significant reduction in proliferation and cytofluorimetric assay demonstrated that extracellular 500 mM GTP induces an arrest in S phase. Immunofluorescence experiments revealed that GTP regulates the expression of acquaporins in plasmamembranes.

Conclusion: 

These results suggest a new role of GTP as a modulator of physiological aspects of the renal system.