Dopamine stimulates ⁴⁵Ca²⁺ uptake through cAMP, PLC/PKC, and MAPKs in renal proximal tubule cells

We have examined the effect of dopamine on Ca²⁺ uptake and its related signaling pathways in primary renal proximal tubule cells (PTCs). Dopamine increased Ca²⁺ uptake in a concentration (>10 ^-10° M) and time- (>8 h) dependent manner. Dopamine-induced increase in Ca²⁺ uptake was prevented by SCH 23390 (a DA₁ antagonist) rather than spiperone (a DA₂ antagonist). SKF 38393 (a DA₁ agonist) increased Ca²⁺ uptake unlike the case with quinpirole (a DA₂ agonist). Dopamine-induced increase in Ca ²⁺ uptake was blocked by nifedipine and methoxyverapamil (L-type Ca²⁺ channel blockers). Moreover, dopamine-induced increase in Ca²⁺ uptake was blocked by pertussis toxin (a G_i protein inhibitor), protein kinase A (PKA) inhibitor amide 14/22 (a PKA inhibitor), and SQ 22536 (an adenylate cyclase inhibitor). Subsequently, dopamine increased cAMP level. The PLC inhibitors (U 73122 and neomycin), the PKC inhibitors (staurosporine and bisindolylmaleimide I) suppressed the dopamine-induced increase of Ca²⁺ uptake. SB 203580 (a p38 MAPK inhibitor) and PD 98059 (a MAPKK inhibitor) also inhibited the dopamine-induced increase of Ca²⁺ uptake. Dopamine-induced p38 and p42/44 MAPK phosphorylation was blocked by SQ 22536, neomycin, and staurosporine. The stimulatory effect of dopamine on Ca²⁺ uptake was significantly inhibited by the NF-κB inhibitors SN50, TLCK, and Bay II-7082. In addition, dopamine significantly increased the level of NF-κB p65, which was prevented by either SQ 22536, neomycin, staurosporine, PD 98059, or SB 203580. Thus, dopamine stimulates Ca²⁺ uptake in PTCs, initially through by G_s coupled dopamine receptors, PLC/PKC, followed by MAPK, and ultimately by NF-κB activation.