Anabolic steroids alter the haemodynamic effects of endurance training and deconditioning in rats.
The haemodynamic effects of endurance training with or without anabolic steroid treatment (nandrolone decanoate, 5.0 mg kg-1 week-1) were studied before and after a six-week sedentary period in anaesthetized, open-chest rats during isoproterenol and CaCl2 loads. In comparison to the control group (CG I, n = 13) endurance training (TG I, n = 10) increased the resting stroke index significantly, end-diastolic pressure and during CaCl2 infusion the end-diastolic and end-systolic volumes. Peripheral resistance decreased in TG I during both inotropic loads but increased in CG I (P less than 0.01 between the groups). After combined endurance training and anabolic steroid treatment (TSG I, n = 16) the haemodynamic state was similar to that in CG I except peripheral resistance which was even higher than in CG I. The heart weight to body weight ratio was significantly greater both in TG I and TSG I than in CG I. After a six-week deconditioning period the haemodynamic values were essentially similar in endurance trained (TG II, n = 10) and in control rats (CG II, n = 12). After the sedentary period, in the simultaneously trained and anabolic steroid-treated group (TSG II, n = 13) stroke index and end-diastolic volume decreased more during isoproterenol load when compared with TG II or CG II (P less than 0.05 between the groups). Peripheral resistance was higher in the TSG II than in the two other groups. In conclusion, the enhanced pumping performance of the heart by increased left ventricular diastolic filling after endurance training is attenuated by simultaneous anabolic steroid treatment which further increases the peripheral resistance. Detraining reversed the main training effects in six weeks and simultaneous anabolic steroid treatment led to a decreased left ventricular filling and to elevated peripheral resistance after the sedentary period.
Karhunen
M K
MK
Department of Physiology, University of Oulu, Finland.
Rämö
M P
MP
Kettunen
R
R
D045930:Anabolic Agents / Q000008:administration & dosage*; D000818:Animals; D001835:Body Weight / Q000187:drug effects; D006321:Heart / Q000033:anatomy & histology; D006439:Hemodynamics / Q000187:drug effects*; D007545:Isoproterenol / Q000008:administration & dosage; D008297:Male; D009929:Organ Size / Q000187:drug effects; D010807:Physical Endurance / Q000187:drug effects*; D005082:Physical Exertion; D051381:Rats; D011919:Rats, Inbred Strains; D013997:Time Factors
D045930:Anabolic Agents; D007545:Isoproterenol