The effects of anabolic steroids on collagen synthesis in rat skeletal muscle and tendon. A preliminary report.

We measured the activities of prolyl 4-hydroxylase and galactosylhydroxylysyl glucosyltransferase (both enzymes of collagen biosynthesis) and the concentration of hydroxyproline in male rat soleus muscle and Achilles tendon during anabolic steroid treatment at 1 and 3 weeks. The rats were treated using a therapeutic dosage or a dosage that was five times the therapeutic level. After 1 week, the activity of prolyl 4-hydroxylase decreased significantly (P less than 0.01) in both treated groups in the soleus muscle, but the activity of galactosylhydroxylsyl glucosyltransferase decreased significantly (P less than 0.05) only in the group given a therapeutic dose. After 3 weeks, the activities were at the control level. In the Achilles tendon, the activity of prolyl 4-hydroxylase and the hydroxyproline concentration decreased significantly (P less than 0.05) in the group given high doses at 3 weeks. Anabolic steroid treatment seems to have at least a transitory effect on collagen biosynthesis in male rat muscle and tendon; in tendon this effect is seen only with high doses.

Cardiac glycosides in the treatment of experimental overdose with calcium-blocking agents.

The ability of digitalis compounds to counteract calcium antagonist overdose was studied in anesthetized dogs (n = 6, 13.5 +/- 0.7 kg) and isolated trabeculae from human hearts (n = 7). Digitalis caused by increasing intracellular cytosolic Ca2+ concentration through Na+/Ca(2+)-exchange across the cell membrane, was postulated to overcome the detrimental effects of excessive slow calcium-channel blockade. In anesthetized dogs, an infusion of verapamil (40 mg/30 min, i.v.) decreased mean arterial pressure from 88 +/- 6 to 66 +/- 6 mm Hg (P < 0.05), reduced systemic vascular resistance (SVR) from 3838 +/- 916 to 2200 +/- 669 dyne.s/cm5 (P < 0.05), and induced total atrio-ventricular (A-V) block in three animals. Stroke volume (SV) remained unchanged. Administration (i.v.) of NaCl (0.9%, 200 ml) and calcium gluconate (100 mg)--to increase the availability of Na+ and Ca(2+)--together with atropine (0.2 mg)--to block the parasympathetic effects of digoxin on A-V conduction--increased left ventricular contractility (15%) but had no significant effects on blood pressure, SV, or A-V block. Digoxin (0.125 mg) returned sinus rhythm in all dogs and, by increasing SVR (P < 0.05) and left ventricular contractility (P < 0.05), returned arterial pressures to baseline. Because of increased afterload, SV decreased slightly (15%) despite increased cardiac contractility. In experiments with isolated trabeculae from diseased human hearts, TA 3090 (Clentiazem) depressed contractile force and ouabain, another glycoside, restored contractile force within 30 min.(ABSTRACT TRUNCATED AT 250 WORDS)

Reversibility of the haemodynamic effects of anabolic steroids in rats.

The haemodynamic effects of 6 weeks nandrolone decanoate treatment (total dose 30 mg.kg-1) (SG I, n = 12) and their reversibility were studied in anaesthetised, open-chest male rats exposed to 5 min isoproterenol (2.5 micrograms.kg-1) and CaCl2 (25.0 mg.kg-1) loads. In SG I, the heart weight and its ratio to body weight were greater than in the untreated rats (CG I, n = 13) (p less than 0.05 and p less than 0.01 respectively). The initial heart rate and the inotropic and chronotropic responses to isoproterenol were lower in SG I than in CG I (p less than 0.05 in all cases). Peripheral resistance decreased during both infusions in SG I but remained unaltered in CG I (p less than 0.05). 6 weeks after finishing anabolic steroid treatment (SG II, n = 11), in the CaCl2-test the ejection fraction (p less than 0.05) and stroke index were smaller than in control rats of the same age (CG II, n = 12). Mean aortic pressure was lower in SG II than in CG II. In the CaCl2-test peripheral resistance was initially higher, but decreased during the infusion in SG II while it increased in CG II (p less than 0.05 in both cases). In conclusion, anabolic steroid treatment reversibly reduces the left ventricular response to isoproterenol. It decreases peripheral vascular tone during inotropic loads. Six weeks after the cessation of treatment, the pumping efficiency of the heart is reduced.