INFLUENCE OF STRIP SIZE AND LOCATION ON CONTRACTILE RESPONSES OF RAT URINARY-BLADDER BODY STRIPS

1. We investigated the influence of strip length and dorsal or ventral location of rat urinary bladder strips on contractile responsiveness. 2. No differences occurred in the contractile responses of 0.5, 1.0 a nd 2.0 cm strips to field stimulation, carbachol, ATP, substance P or to KCI when the data were expressed as either absolute tension or as t ension per cross-sectional area. However, correction for strip mass re sulted in significant decreases in the contractile responses of the 2. 0-cm strips compared with the 0.5-cm strips. 3. No differences occurre d in length-tension curves for ventral and dorsal bladder strips, even though the strips from the dorsal surface appeared thinner than those from the ventral surface. 4. Strips from the ventral surface exhibite d more variability in response to field stimulation and were less sens itive to atropine pre-treatment than were those from the dorsal surfac e. They were also less sensitive to the contractile effects of carbach ol than dorsal strips. Dorsal and ventral strips were equally responsi ve to ATP, substance P and KCI. 5. Our data indicate that the contract ile responsiveness of rat urinary bladder strips is independent of str ip length. Although there are some differences between the cholinergic responsiveness of strips from the ventral and dorsal surfaces of the bladder, the differences are so small that for most studies they will probably have no influence on data interpretation.