Effect of bradykinin and histamine on the membrane voltage, ion conductances and ion channels of human glomerular epithelial cells (hGEC) in culture

Abstract

The effects of bradykinin (BK) and histamine (Hist) on the membrane voltage (Vm), ion conductances and ion channels of cultured human glomerular epithelial cells (hGEC) were examined with the nystatin patch clamp technique. Cells were studied between passage 3 and 20 in a bath rinsed with Ringer-like solution at 37 degrees C. The mean value of Vm was -41 +/- 0.5 mV (n = 189). BK (10(-6) mol/l, n = 29) and Hist (10(-5) mol/l, n = 55) induced a rapid transient hyperpolarization by 15 +/- 1 mV and 18 +/- 1 mV, respectively. The hyperpolarization was followed by a long lasting depolarization by 6 +/- 1 mV (BK 10(-6) mol/l) and 7 +/- 1 mV (Hist 10(-5) mol/l). The ED50 was about 5 x 10(-8) mol/l for BK and 5 x 10(-7) mol/l for Hist. In the presence of both agonists, increases of outward and inward currents were observed. A change in the extracellular K+ concentration from 3.6 to 30 mmol/l depolarized Vm by 8 +/- 1 mV and completely inhibited the hyperpolarizing effect of both agents (n = 11). Reduction of extracellular Cl- concentration from 145 to 30 mmol/l led to a depolarization by 2 +/- 1 mV (n = 25). In 30 mmol/l Cl- the depolarizations induced by BK (10(-7) mol/l) and Hist (10(-6) mol/l) were augmented to 9 +/- 2 mV (n = 14) and to 10 +/- 2 mV (n = 11), respectively.(ABSTRACT TRUNCATED AT 250 WORDS)