Dopamine depolarizes podocytes via a D1-like receptor

Background. Dopamine influences glomerular haemodynamics and dopamine receptors have been demonstrated in the glomerulus, but little is known about the cellular effects of dopamine in glomerular cells. The aim of this study was to investigate the influence of dopamine on the cellular functions of podocytes. Methods. The effect of dopamine on membrane voltage was investigated in differentiated mouse podocytes. The membrane voltage was measured using the patch clamp technique. Reverse transcribed-polymerase chain reaction (RT-PCR) studies were performed to investigate the expression of dopamine receptor mRNA in mouse glomeruli and podocytes. Results, The addition of dopamine (100nM-1000 mu M) caused a concentration-dependent depolarization of podocytes (EC50 approximate to 10 mu M). Like dopamine, the selective agonist of the D1-like receptor, SKF 82958, depolarized podocytes in a concentration-dependent manner. (EC50 approximate to 50 mu M). SKF 82958 stimulated a time-and concentration-dependent accumulation of cyclic adenosine 3',5'-monophosphate (cAMP) in podocytes (EC50 approximate to 5 mu M). RT-PCR studies with primers derived from mouse sequences amplified mouse mRNA for the D1-like and the D2-like receptor in glomeruli, which were obtained by the sieve technique, whereas only mRNA for the D1-like receptor was detected in cultured mouse podocytes. Conclusion. The data indicate that dopamine induces a cAMP-dependent depolarization via a D1-like receptor in podocytes.