Voltage‐operated Ca2+ currents and Ca2+‐activated Cl– currents in single interstitial cells of the guinea‐pig prostate. (September 2014)

• Record Type: Journal Article
• Authors: Lang, Richard J.; Tonta, Mary A.; Takano, Hiromichi; Hashitani, Hikaru
• Is Part Of: BJU international. Volume 114:Number 3(2014:Sep.)
• Page Start: 436
• Page End: 446
• Publication Date: 2014-09
• Subjects: Genitourinary organs -- Diseases -- Periodicals; Genitourinary organs -- Surgery -- Periodicals; Urology -- Periodicals; 616.6
• DOI: 10.1111/bju.12656
• Languages: English
• ISSNs: 1464-4096

Abstract

<abstract abstract-type="main"> <title> <x xml:space="preserve">Abstract</x> </title> <sec id="bju12656-sec-5001" sec-type="section"> <title>Objective</title> <p>To investigate the expression of 'T‐type' and 'L‐type' voltage‐operated Ca<sup>2</sup><sup>+</sup> channels in single interstitial cells of the guinea‐pig prostate.</p> </sec> <sec id="bju12656-sec-5002" sec-type="section"> <title>Material and Methods</title> <p>Whole‐cell and perforated patch‐clamp techniques were applied to prostatic interstitial cells (PICs) dispersed using collagenase.</p> </sec> <sec id="bju12656-sec-5003" sec-type="section"> <title>Results</title> <p>In contrast to prostatic myocytes, PICs under voltage clamp and filled with K<sup>+</sup> (130 m<sc>m</sc>) were distinguished by the absence of a voltage‐operated transient outward K<sup>+</sup> current or spike discharge upon membrane depolarisation when under current clamp. Depolarisation of Cs<sup>+</sup>‐filled PICs evoked an inward current at potentials positive to −60 mV, which peaked in amplitude near 0 mV. This inward current increased when Ba<sup>2+</sup> (5 m<sc>m</sc>) replaced the external Ca<sup>2</sup><sup>+</sup> (1.5 m<sc>m</sc>) and displayed a variable sensitivity to the inhibitory actions of conditioning depolarisations to −40 mV applied before the test depolarisation or to 1 μ<sc>m</sc> nifedipine, the 'L‐type' Ca<sup>2</sup><sup>+</sup> channel blocker. A residual inward current recorded in nifedipine was blocked by 10 μ<sc>m</sc> Ni<sup>2</sup><sup>+</sup>. Cs<sup>+</sup>‐filled PICs also displayed a slowly inactivating outward current that was little affected by nifedipine, reduced by the Cl<sup>–</sup> channel blocker, niflumic acid (10 μ<sc>m</sc>) and blocked by Ba<sup>2</sup><sup>+</sup> or a conditioning depolarisation.</p> </sec> <sec id="bju12656-sec-5004" sec-type="section"> <title>Conclusion</title> <p>PICs express both a small 'T‐type' Ca<sup>2</sup><sup>+</sup> channel current (I<sub>Ca</sub>) and a large 'L‐type' I<sub>Ca</sub>. Ca<sup>2</sup><sup>+</sup> influx through 'T‐type' I<sub>Ca</sub> was an essential trigger for the activation of a Ca<sup>2</sup><sup>+</sup>‐activated Cl<sup>–</sup>‐selective current. The dependence of PIC Ca<sup>2</sup><sup>+</sup> signalling on 'T‐type' and 'L‐type' I<sub>Ca</sub> is unique compared with other interstitial cells of the urogenital tract and may well be pharmaceutically exploitable.</p> </sec> </abstract>