PT  - JOURNAL ARTICLE
AU  - Sand, Carsten
AU  - Michel, Martin C.
TI  - Bradykinin Contracts Rat Urinary Bladder Largely Independently of Phospholipase C
AID  - 10.1124/jpet.113.208025
DP  - 2014 Jan 01
TA  - Journal of Pharmacology and Experimental Therapeutics
PG  - 25--31
VI  - 348
IP  - 1
4099  - http://jpet.aspetjournals.org/content/348/1/25.short
4100  - http://jpet.aspetjournals.org/content/348/1/25.full
SO  - J Pharmacol Exp Ther2014 Jan 01; 348
AB  - Several receptor systems in the bladder causing detrusor smooth muscle contraction stimulate phospholipase C (PLC). PLC inhibition abolishes bladder contraction via P2Y6 but not that via M3 muscarinic receptors, indicating a receptor-dependent role of PLC. Therefore, we explored the role of PLC in rat bladder contraction by bradykinin. The PLC inhibitor U 73,122 [1-(6-[([17β]-3-methoxyestra-1,3,5[10]-trien-17-yl)-amino]hexyl)-1H-pyrrole-2,5-dione] did not affect the bradykinin response to a significantly greater degree than its inactive analog U 73,343 [10 μM each; 1-(6-[-([17β]-3-methoxyestra-1,3,5[10]-trien-17-yl)-amino]hexyl)-2,5-pyrrolidinedione], whereas the phospholipase D inhibitor butan-1-ol relative to its inactive control butan-2-ol caused a weak but significant inhibition (0.3% each). The cytosolic phospholipase A2 inhibitor arachidonyltrifluoromethyl ketone (300 μM) and the cyclooxygenase inhibitor indomethacin (10 μM) caused strong inhibition of the bradykinin response. The L-type Ca2+ channel blocker nifedipine (10–100 nM) concentration-dependently caused strong inhibition, whereas only a small but significant inhibition was seen with SK&F 96,365 [10 μM; 1-[β-[3-(4-methoxyphenyl)propoxy]-4-methoxyphenethyl]-1H-imidazole HCl], an inhibitor of receptor-operated Ca2+ channels. Several protein kinase C inhibitors yielded an equivocal picture (inhibition by 10 μM bisindolylmaleimide I and 1 μM calphostin but not by 10 μM chelerythrine). The rho kinase inhibitor Y 27,632 [1–10 μM; trans-4-[(1R)-1-aminoethyl]-N-4-pyridinylcyclohexanecarboxamide] caused a strong and concentration-dependent inhibition of the bradykinin response. Our data support that not only M3 but also bradykinin receptors cause bladder contraction by a largely PLC-independent mechanism. Both responses strongly involve L-type Ca2+ channels and rho kinase, whereas only the bradykinin response additionally involves the phospholipase A2/cyclooxygenase pathway.