Respiratory and cardiac responses to exercise-simulating peripheral perfusion in endurance trained and untrained rats. I. Reflex responses and changes in perfusion outflow.
Ventilatory and circulatory drives elicited by exercise-simulating perfusion of the circulatory isolated hindleg were examined in 10 trained (TR) and untrained (UTR) rats. TR were submitted to endurance training on a motordriven treadmill (30.min-1 at a grade of 10%, 5 days a week for 30 min). Exercise was simulated by perfusion with modified tyrode solutions: I.) hypoxic, enriched with lactic acid (15 mmol.l-1), II.) normoxic, enriched with lactic acid. III.) hypoxic without lactic acid. Perfusion was performed in anaesthetized animals through cannulae in the femoral artery and vein; the hindled was connected to the rest of the body only by nerve and bone. 10 min of control perfusion (normoxic tyrode solution) was followed by a 20 min test period and another 10 min control perfusion. Apart from heart rate (HR), respiratory rate (RR) and several outflow parameters were measured ([K+], [Na+], [lactate], pH, PO2, PCO2). During control period HR was slightly higher in UTR than in TR (375.5 +/- 3.9 (SE) vs. 364.1 +/- 5.5 beats/min-1, p less than 0.6 n.s.), and RR in UTR was significantly higher than those in TR (61.5 +/- 0.4 bpm vs. 55.5 +/- 3.9 breaths.min-1, p less than 0.001). During the test periods both HR and RR in UTR increased significantly while in TR they did not (e.g. in series I mean HR and RR in UTR increased by 8.9 +/- 1.2 beats.min-1 and 1.4 +/- 0.1 breaths.min-1 respectively, whereas in TR the changes were - 2.9 +/- 1.5 beats/min-1 and -0.8 +/- 0.2 breaths.min-1.(ABSTRACT TRUNCATED AT 250 WORDS)
Thimm
F
F
Physiologisches Institut der Deutschen Sporthochschule Köln, Federal Republic of Germany.
Gerber
B
B
D000818:Animals; D006321:Heart / Q000502:physiology*; D006339:Heart Rate; D006863:Hydrogen-Ion Concentration; D000860:Hypoxia / Q000503:physiopathology; D007552:Isotonic Solutions; D007773:Lactates / Q000097:blood / Q000494:pharmacology; D008297:Male; D010101:Oxygen Consumption; D010477:Perfusion; D010805:Physical Conditioning, Animal; D010807:Physical Endurance; D005082:Physical Exertion; D051381:Rats; D011919:Rats, Inbred Strains; D012018:Reflex / Q000502:physiology; D012119:Respiration
D007552:Isotonic Solutions; D007773:Lactates; C037692:Tyrode's solution