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Increased intra‐abdominal pressure alters the contractile properties of rabbit bladder
Author(s) -
Bingölkolog¯lu M.,
Sara Y.,
Ertunç M.,
Onur R.,
Büyükpamukçu N.,
Tanyel F.C.
Publication year - 2000
Publication title -
bju international
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.773
H-Index - 148
eISSN - 1464-410X
pISSN - 1464-4096
DOI - 10.1046/j.1464-410x.2000.00429.x
Subject(s) - carbachol , contractility , endocrinology , stimulation , medicine , urinary bladder , chemistry , anesthesia
Objective To evaluate the effects of increased intra‐abdominal pressure (IAP) on the contractility of the rabbit bladder, as the dynamics of the bladder may be impaired in conditions associated with a high IAP, e.g. constipation and pregnancy. Material and methods The study comprised 22 adult male New Zealand rabbits; six served as the control group, eight had an IAP of 7 cmH 2 O imposed for 10 days by instilling air into the abdominal cavity and this IAP was maintained for 60 days in a further eight rabbits. After treatment, the rabbits were killed, and the bladders removed and cut into 3 × 12 mm strips. The contractile activity of the muscle strips was then recorded isometrically. Electrical field stimulation (EFS) was applied using a pair of platinum ring electrodes in trains of 3 s duration every 100 s (1 ms, 100 V, 2–100 Hz). Contractile responses to carbachol and isotonic KCl were also evaluated. Results EFS induced a frequency‐dependent increase in contractile activity in all bladder strips. Ten days of high IAP resulted in an increased responsiveness to EFS, but high IAP for 60 days reduced the EFS‐induced responses to the control levels. Carbachol (10 −9 –10 −3 mol/L) elicited concentration‐dependent contractions in all groups. From the concentration‐response curves of carbachol, the log EC 50 values (the concentration producing half the maximum effect) of the control and 60‐day treated animals were comparable, at −6.24 (0.05) and −6.25 (0.04), respectively. However, the log EC 50 of the 10 day‐treated group was −4.97 (0.08) and significantly ( P < 0.01) lower than that of both groups. Isotonic KCl produced contractions in all preparations; these contractions in the control and 60‐day treated animals were similar, while the 10 day‐treated group had significantly ( P < 0.05) higher contraction amplitudes. Conclusion Increased IAP alters the contractile properties of the bladder and its responsiveness to carbachol and KCl. As the intravesical pressure closely reflects the IAP, both should be increased in the present experimental design.