Ba. O'Reilly et al., A quantitative analysis of purinoceptor expression in the bladders of patients with symptomatic outlet obstruction, BJU INT, 87(7), 2001, pp. 617-622
Objective To compare the expression of the seven known P2X receptors in hum
an bladder from male patients with detrusor instability caused by symptomat
ic bladder outlet obstruction with that from control bladders, using a quan
titative reverse transcription-polymerase chain reaction (RT-PCR) method.
Patients and methods Real-time quantitative RT-PCR provides a system for de
tecting and analysing RNA. Bladder biopsies were obtained from nine patient
s undergoing prostate surgery and control biopsies were obtained From eight
age-matched men undergoing routine bladder endoscopy studies, and who were
asymptomatic. Total RNA was extracted from each sample and 10 ng of this u
sed for individual PCR reactions. The expression levels of the seven P2X ge
nes in the total RNA were then determined.
Results In the control bladder, P2X(1) was by far the predominant purinergi
c receptor at the RNA level, the remainder consistently present in the orde
r P2X(1) >> P2X(4) > P2X(2) >P2X(7) > P2X(5) >> P2X(3) = P2X(6) = 0. Calpon
in, a smooth muscle-specific protein, was used as a marker for smooth muscl
e content. In bladder from symptomatic patients. the P2X(1)/ calponin ratio
was greater than that in controls (P=0.016). There appeared to be no diffe
rence in P2X(2), but P2X(4), P2X(5), and P2X(7) were all greater in the sym
ptomatic bladder than in the controls. although these differences were not
significant.
Conclusion P2X(1) is the predominant purinoceptor subtype in the human male
bladder, consistent with pharmacological evidence. The amount of P2X(1) re
ceptor per smooth muscle cell is greater in the obstructed than in control
bladder, suggesting an increase in purinergic function in the unstable blad
der arising from bladder outlet obstruction.