Pacemaker activity in urethral interstitial cells is not dependent on capacitative calcium entry.
The aim of the present study was to investigate the properties and role of capacitative Ca(2+) entry (CCE) in interstitial cells (IC) isolated from the rabbit urethra. Ca(2+) entry in IC was larger in cells with depleted intracellular Ca(2+) stores compared with controls, consistent with influx via a CCE pathway. The nonselective Ca(2+) entry blockers Gd(3+) (10 microM), La(3+) (10 microM), and Ni(2+) (100 microM) reduced CCE by 67% (n = 14), 65% (n = 11), and 55% (n = 9), respectively. These agents did not inhibit Ca(2+) entry when stores were not depleted. Conversely, CCE in IC was resistant to SKF-96365 (10 microM), wortmannin (10 microM), and nifedipine (1 microM). Spontaneous transient inward currents were recorded from IC voltage-clamped at -60 mV. These events were not significantly affected by Gd(3+) (10 microM) or La(3+) (10 microM) and were only slightly decreased in amplitude by 100 microM Ni(2+). The results from this study demonstrate that freshly dispersed IC from the rabbit urethra possess a CCE pathway. However, influx via this pathway does not appear to contribute to spontaneous activity in these cells.
Bradley
Eamonn
E
Smooth Muscle Research Centre, Dundalk Institute of Technology, Dundalk, Co. Louth, Ireland.
Hollywood
Mark A
MA
McHale
Noel G
NG
Thornbury
Keith D
KD
Sergeant
Gerard P
GP
D000818:Animals; D001683:Biological Clocks / Q000502:physiology*; D002118:Calcium / Q000378:metabolism*; D002121:Calcium Channel Blockers / Q000494:pharmacology; D005260:Female; D005682:Gadolinium / Q000494:pharmacology; D007093:Imidazoles / Q000494:pharmacology; D007811:Lanthanum / Q000494:pharmacology; D008297:Male; D008564:Membrane Potentials / Q000187:drug effects / Q000502:physiology; D032389:Myocytes, Smooth Muscle / Q000502:physiology*; D009532:Nickel / Q000494:pharmacology; D018408:Patch-Clamp Techniques; D011817:Rabbits; D014521:Urethra / Q000166:cytology* / Q000502:physiology*
D002121:Calcium Channel Blockers; D007093:Imidazoles; D007811:Lanthanum; D009532:Nickel; D005682:Gadolinium; C063159:1-(2-(3-(4-methoxyphenyl)propoxy)-4-methoxyphenylethyl)-1H-imidazole; D002118:Calcium