We hypothesized that the calcineurin-nuclear factor of activated T-cells (NFAT) pathway is activated following partial bladder outlet obstruction (pBOO), which would allow for pharmacologic treatment to prevent the ensuing bladder wall hypertrophy. Using a model of pBOO in male mice, we were able to demonstrate increased nuclear importation of the transcription factors NFAT and myocyte enhanching factor 2 both of which are under control of calcineurin in both the whole bladder wall as well as the urothelium. We further confirmed that this pathway was activated using transgenic mice containing an NFAT-luciferase reporter construct. Mice were randomized following pBOO to treatment with or without cyclosporine A (CsA), a known inhibitor of calcineurin. The bladder-to-body mass ratio (mg bladder wt/g body wt) of 0.95 ± 0.03 in shams increased to 3.1 ± 0.35 following pBOO, and it dropped back to 1.7 ± 0.22 in the CsA+ group (P < 0.001). Luciferase values (RLU) of 1,130 ± 133 in shams increased to 2,010 ± 474 following pBOO and were suppressed to 562 ± 177 in the CsA+ group (P < 0.05). The myosin heavy chain mRNA (A/B) isoform ratio of 0.07 ± 0.03 in shams increased to 1.04 ± 0.19 following pBOO but it diminished to 0.24 ± 0.1 in the CsA+ group (P < 0.001). In vitro whole organ physiology studies demonstrated improved responses in those bladders from mice treated with CsA. The mRNAs for all four known calcineurin-responsive NFAT isoforms are expressed in the bladder wall, although NFATc(3) and NFATc(4) predominate. Both NFATc3 and NFATc4 are expressed in urothelial as well as smooth muscle cells. We conclude that pBOO activates the calcineurin-NFAT pathway and that CsA treatment decreased bladder hypertrophy, shifted the pattern of myosin isoform mRNA expression back toward that seen in normal controls, and resulted in improved in vitro whole organ performance.

Male albino rats of the Wistar Institute strain with an average beginning weight of 250 gm were exercised from 5–8 weeks on a training regimen consisting of swimming for 1/2 hour daily. Pair-fed, nonswimming animals served as controls. All exercised animals gained less body weight than did their controls. The adrenals and heart ventricles of the exercised animals hypertrophied significantly ( P < 0.01), while the skeletal muscles (gastrocnemii) did not. Succinic dehydrogenase activities (reduction of ferricytochrome c) were determined in the heart ventricles and the gastrocnemii. The results were expressed in terms of unit activities, actual total activities and relative total activities. The exercise, whether for 5, 6, 7 or 8 weeks, did not significantly alter the unit and actual total activities of either tissue, or the relative total activities of skeletal muscles, but did significantly increase the relative total activities of the heart ventricle ( P < 0.02).

Young adult male Wistar rats with an average beginning weight of 294 gm had a segment of the right sciatic nerve removed. The nonoperated left leg served as a control. Succinate-cytochrome c reductase, cytochrome oxidase and aldolase activities, total RNA-P, total DNA-P and total protein were determined for both the denervated and control gastrocnemii muscles. The results for the enzymatic activities were expressed in terms of unit activity and total activity. The denervated muscles had significantly less enzymatic activity, RNA-P, wet weight and protein content ( P <0.02). The losses apparently occurred in the cytoplasmic portion of the muscle fiber. However, this loss was not revealed histologically in the cross section of the muscle fiber. Expression of the results on the basis of unit protein, nitrogen or RNA-P did not significantly alter the results.

Adult male albino rats of the Sprague-Dawley strain, with an approximate initial body weight of 340 g were exercised for 5 weeks on a training program consisting of swimming for one-half hour daily in water at 37 C. Pair-fed, nonexercised animals served as controls. All exercised animals gained less body weight than did their controls. The adrenals and heart ventricles of the exercised animals were enlarged, whereas the kidneys and gastrocnemii were smaller. Unit and total protein of the heart ventricles were greater for the exercised animals. Lactic dehydrogenase activities were determined in the heart ventricles and gastrocnemii. The activities were expressed in terms of unit, actual total, and relative total values. After exercise, the activities of the heart ventricles were increased, whereas those of the skeletal muscle were unchanged.

Young adult male Wistar rats with an average initial weight of 250 gm were exercised from 5 to 8 weeks on a training regimen consisting of swimming one-half hour daily. Pair-fed, nonswimming animals served as controls. The unit protein of the heart ventricles and gastrocnemii (mg protein/gm wet weight of organ) was in general greater for the exercised animals. Aldolase activities were determined in the heart ventricles and the gastrocnemii. The results were expressed in terms of unit activities, actual total activities and relative total activities. The exercise significantly altered the unit and relative total activities of both the heart ventricles and skeletal muscle ( P < 0.05 or < 0.01), except for the 8th week in heart, and the actual total activities of the heart ( P < 0.01), except for the 8th week.