Effects of Noradrenaline on the Membrane Potential of Prostatic Neuroendocrine Cells of Rat.
- Author:
Jun Hee KIM
1
;
Sun Young SHIN
;
Dae Yong UHM
;
Sung Joon KIM
Author Information
1. Department of Physiology, Sungkyunkwan University School of Medicine, Suwon 440-746, Korea.
- Publication Type:Original Article
- Keywords:
Prostate;
Neuroendocrine cel;
Noradrenaline;
Membrane potential;
Patch clamp
- MeSH:
Animals;
Cytoplasm;
Cytosol;
Fluorescence;
Fura-2;
Membrane Potentials*;
Membranes*;
Neuroendocrine Cells*;
Norepinephrine*;
Prostate;
Rats*
- From:The Korean Journal of Physiology and Pharmacology
2003;7(1):47-52
- CountryRepublic of Korea
- Language:English
-
Abstract:
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 alpha 1- and alpha 2-ARs, signaling the release of stored Ca2+ and the inhibition of N-type Ca2+ 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, 1 micro M) 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 Ca2+ concentration ([Ca2+]c), measured by the fura-2 fluorescence, and the voltage clamp study showed the presence of charybdotoxin-sensitive Ca2+ -activated K+ 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 Ca2+ -activated K+ current might partly explain the depolarization and hyperpolarization, respectively.
