Therapeutic potential of muscle growth promoters in a stress urinary incontinence model
AMERICAN JOURNAL OF PHYSIOLOGY-RENAL PHYSIOLOGY
Authors: Yang, Jun; Balog, Brian; Deng, Kangli; Hanzlicek, Brett; Rietsch, Anna; Kuang, Mei; Hatakeyama, Shinji; Lach-Trifilieff, Estelle; Zhu, Hui; Damaser, Margot S.
Abstract
Weakness of urinary sphincter and pelvic floor muscles can cause insufficient urethral closure and lead to stress urinary incontinence. Bimagrumab is a novel myostatin inhibitor that blocks activin type II receptors. inducing skeletal muscle hypertrophy and attenuating muscle weakness. beta(2)-Adrenergic agonists, such as 5-hydroxybenzothiazolone derivative (5-110B) and clenbuterol, can enhance muscle growth. We hypothesized that promoting muscle growth would increase leak point pressure (LPP) by facilitating muscle recovery in a dual-injury (DI) stress urinary incontinence model. Rats underwent pudendal nerve crush (PNC) followed by vaginal distension (VD). One week after injury, each rat began subcutaneous (0.3 mL/rat) treatment daily in a blinded fashion with either bimagrumab (DI + Bim), clenbuterol (DI + Clen), 5-HOB (DI + 5-HOB), or PBS (DI + PBS). Sham-injured rats underwent sham PNC + VD and received PBS (sham + PBS). After 2 wk of treatment, rats were anesthetized for LPP and external urethral sphincter electromyography recordings. Hindlimb skeletal muscles and pelvic floor muscles were dissected and stained. At the end of 2 wk of treatment, all three treatment groups had a significant increase in body weight and individual muscle weight compared with both sham-treated and sham-injured rats. LPP in DI + Bim rats was significantly higher than LPP of DI + PBS and DI + Clen rats. There were more consistent urethral striated muscle fibers, elastin fibers in the urethra, and pelvic muscle recovery in DI + Bim rats compared with DI + PBS rats. In conclusion, bimagrumab was the most effective for increasing urethral pressure and continence by promoting injured external urethral sphincter and pelvic floor muscle recovery.
Chronic clenbuterol administration negatively alters cardiac function
MEDICINE AND SCIENCE IN SPORTS AND EXERCISE
Authors: Sleeper, MM; Kearns, CF; McKeever, KH
Abstract
Purpose: Chronic administration of pharmacological levels of beta2-agonists have been shown to have toxic effects on the hearth however, no data exist on cardiac function after chronic clenbuterol administration. The purpose of this study was to examine the effect of therapeutic levels of clenbuterol on cardiac performance, Methods: Twenty unfit Standardbred mares were divided into four experimental groups: clenbuterol (2.4 mug.kg(-1) twice daily 5 d.wk(-1)) plus exercise (20 min at 50% VO2max) (CLENEX; N = 6), clenbuterol (CLEN; N = 6), exercise (EX: N = 4), and control (CON; N = 4). M-mode and two-dimensional echocardiography (2.5-MHz sector scanner transducer) were used to measure cardiac size and function before and immediately after an incremental exercise test, before and after 8 wk of drug and/or exercise treatments. Results: After treatment, CLENEX and CLEN demonstrated significantly higher left ventricular internal dimension (LVD) at end diastole (+/-23.7 +/-4.8%; +25.6 +/- 4.1%), LVD at end systole (+29.2 +/- 8.7%; +40.1 +/- 7.9%), interventricular septal wall thickness (IVS) at end diastole (+28.9 +/- 11-0%; +30.7 +/- 7.0%), IVS at end systole (+29.2 +/- 8.7%; +40.1 +/- 7.9%), and left ventricular posterior wall systolic thickness (+43.1 +/- 14 %; +45.8 +/- 14.1%). CLENEX and CLEN had significantly increased aortic root dimensions (+29.9 +/- 6.1%; +24.0 +/- 1.7%), suggesting increased risk of aortic rupture. Conclusion: Taken together, these data indicate that chronic clenbuterol administration may negatively alter cardiac function.