Changes in intracellular calcium concentration and P2X1 receptor expression in hypertrophic rat urinary bladder smooth muscle
Abstract
Contractile responses to purinergic activation in the urinary bladder are altered in outflow obstruction (O). We determined if the lowered contractile response to adenosine triphosphate (ATP) in obstructed rat urinary bladder was due to changes in calcium handling or in P2X1 purinoceptor density. O was created in rat by partial ligature of the urethra, with non-obstructed rats as controls (C). Force and intracellular calcium were measured in bladder strips activated with ATP. Tissue was sectioned for light and electron microscopy and analyzed with Western blot using a P2X1 antibody. Bladder weight increased from 66 +/- 3 (C) to 206 +/- 17 mg (O) (n = 6). ATP gave a transient contractile response which was decreased in the obstructed strips (C: 161 +/- 20; O: 63 +/- 16% of high-K+ force). Intracellular calcium concentration after ATP activation in the obstructed bladder muscle was about 50% of that in the control preparations (C: 669 +/- 110; O: 335 +/- 59 nM). Half-time for calcium influx was increased in the O group. P2X1 immunoreactivity per unit bladder weight was similar in the two groups. Cell membrane area per unit wet weight was decreased in the O group. Attenuated contractile responses to ATP in obstructed rat urinary b...Continue Reading
References
Evidence for purinergic neurotransmission in human urinary bladder affected by interstitial cystitis
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