Ca(2+) channel properties in smooth muscle cells of the urinary bladder from pig and human.
Ca(2+) channel properties of pig and human bladder smooth muscle were investigated utilizing standard whole-cell patch clamp techniques. Both the amplitude obtained and the current density of Ca(2+) channel current evoked by step depolarization were larger in human than in pig myocytes. The inward currents were sensitive to an L-type Ca(2+) channel antagonist, nifedipine, the effects of which were not significantly different between species. In both species, prior application of ATP (0.1 mM) had no effect on activation of this voltage-sensitive channel current, while a muscarinic receptor agonist, carbachol (0.1 mM), significantly attenuated the amplitude of this current. Furthermore, inclusion of GDP-beta-S or Heparin in the pipette abolished or had no effect on the suppression of Ca(2+) current by carbachol, respectively. These results forward the pig as a good model for the human in detrusor Ca(2+) channel properties, especially with regard to neural modulation, although voltage-sensitive Ca(2+) channels seem to make greater contribution in human bladder physiology.
Kajioka
Shunichi
S
University Department of Pharmacology, University of Oxford, Mansfield Road, Oxford, OX1 3QT, UK.
Nakayama
Shinsuke
S
McMurray
Gordon
G
Abe
Kihachiro
K
Brading
Alison F
AF
D000255:Adenosine Triphosphate / Q000494:pharmacology; D000818:Animals; D002121:Calcium Channel Blockers / Q000494:pharmacology; D020746:Calcium Channels, L-Type / Q000187:drug effects* / Q000502:physiology; D002217:Carbachol / Q000493:pharmacokinetics; D018929:Cell Culture Techniques; D018679:Cholinergic Agonists / Q000494:pharmacology; D006801:Humans; D023421:Models, Animal; D032389:Myocytes, Smooth Muscle / Q000187:drug effects* / Q000502:physiology; D009543:Nifedipine / Q000494:pharmacology; D018408:Patch-Clamp Techniques; D011983:Receptors, Purinergic / Q000187:drug effects; D013045:Species Specificity; D013552:Swine; D001743:Urinary Bladder / Q000187:drug effects* / Q000502:physiology
D002121:Calcium Channel Blockers; D020746:Calcium Channels, L-Type; D018679:Cholinergic Agonists; D011983:Receptors, Purinergic; D000255:Adenosine Triphosphate; D002217:Carbachol; D009543:Nifedipine