Effects of Noradrenaline on the Membrane Potential of Prostatic Neuroendocrine Cells of Rat
Effects of Noradrenaline on the Membrane Potential of Prostatic Neuroendocrine Cells of Rat
- Jun Hee Kim Sun Young Shin Dae-Yong Uhm Sung Joon Kim
- 대한생리학회-대한약리학회
- The Korean Journal of Physiology & Pharmacology
- 제7권 제1호
- 등재여부 : KCI등재
- 2003.01
- 47 - 52 (6 pages)
The prostate gland contains numerous neuroendocrine cells that are believed to influence the function of the prostate gland. Our recent study demonstrated the expression of both α1- and α2-ARs, signaling the release of stored Ca<SUP>2⁢</SUP> and the inhibition of N-type Ca<SUP>2⁢</SUP> channels, respectively, in rat prostate neuroendocrine cells (RPNECs). In this study, the effects of NA on the resting membrane potential (RMP) of RPNECs were investigated using a whole-cell patch clamp method. Fresh RPNECs were dissociated from the ventral lobe of rat prostate and identified from its characteristic shape; round or oval shape with dark cytoplasm. Under zero-current clamp conditions with KCl pipette solution, the resting membrane potential (RMP) of RPNECs was between ⁣35 mV and ⁣85 mV. In those RPNECs with relatively hyperpolarized RMP (<⁣60 mV), the application of noradrenaline (NA, 1μM) depolarized the membrane to around ⁣40 mV. In contrast, the RPNECs with relatively depolarized RMP (>⁣45 mV) showed a transient hyperpolarization and subsequent fluctuation at around ⁣40 mV on application of NA. Under voltage clamp conditions (holding voltage, ⁣40 mV) with CsCl pipette solution, NA evoked a slight inward current (<⁣20 pA). NA induced a sharp increase of cytosolic Ca<SUP>2⁢</SUP> concentration ([Ca<SUP>2⁢</SUP>]<SUB>c</SUB>), measured by the fura-2 fluorescence, and the voltage clamp study showed the presence of charybdotoxin-sensitive Ca<SUP>2⁢</SUP>-activated K<SUP>⁢</SUP> currents. In summary, adrenergic stimulation induced either depolarization or hyperpolarization of RPNECs, depending on the initial level of RMP. The inward current evoked by NA and the Ca<SUP>2⁢</SUP>-activated K<SUP>⁢</SUP> current might partly explain the depolarization and hyperpolarization, respectively.