[Tail-suspended rats with inguinal canal ligation and their myocardial function]

To examine the effect of testosterone level on myocardial contractility and to prevent the testis from sliding into abdominal cavity when subjected to tail-suspension, a new tail-suspended model of rat with its inguinal canal ligated was made. Rats suspended for 4 w without inguinal canal ligation (SUS) exhibited significant reduction in weight of testis (CON 1.70 +/- 0.19 g; SUS 0.60 +/- 0.16 g) and in serum testosterone level (CON 99.5 +/- 32.7 ng/dl; SUS 23.0 +/- 13.2 ng/dl) (P<0.01). Unexpectedly, 4 w tail-suspension of rats with inguinal canal ligation (ST) also showed significant changes in testis weight (1.21 +/-0.30 g) and serum testosterone level (40.7 +/- 32.6 ng/dl). A significant decrease of the developed tension of the papillary muscle of the left cardiac ventricle was observed in SUS and ST group as compared with controls (CON: 3.93 +/- 0.42 g/mm2, SUS: 2.54 +/- 0.85 g/mm2, ST: 2.60 +/- 0.73 g/mm2). There was no relationship between the developed tension and serum testosterone level. It suggests that the decrease of blood supply of the testis may result in an atrophy of the testis in ST group.