Effects of exercise training on the vascular reactivity of the whole kidney circulation in rabbits

• Published in: Journal of applied physiology (1985) Vol. 97; no. 2; pp. 683 - 688
• Main Authors: Moraes, Roger De, Gioseffi, Giovanni, Nobrega, Antonio C. L, Tibirica, Eduardo
• Format: Journal Article
• Language: English
• Published: Bethesda, MD Am Physiological Soc 01-08-2004; American Physiological Society
• Subjects: Acetylcholine - pharmacology; Animals; Biological and medical sciences; Endothelium, Vascular - physiology; Enzyme Inhibitors - pharmacology; Exercise; Female; Fundamental and applied biological sciences. Psychology; In Vitro Techniques; Kidneys; Male; Microcirculation - drug effects; Microcirculation - physiology; NG-Nitroarginine Methyl Ester - pharmacology; Nitric oxide; Nitroprusside - pharmacology; Perfusion; Physical Conditioning, Animal - physiology; Physical Exertion - physiology; Rabbits; Renal Circulation - drug effects; Renal Circulation - physiology; Vasodilator Agents - pharmacology; Physical exercise; Vertebrata; Mammalia; Physical training; Reactivity; Urinary system; chronic exercise; Rabbit; Lagomorpha; endothelial dysfunction; isolated perfused rabbit kidney; Kidney
• ISSN: 8750-7587; 1522-1601
• DOI: 10.1152/japplphysiol.00923.2003

1 Departamento de Fisiologia e FarmacodinÂmica, Instituto Oswaldo Cruz, FIOCRUZ, 21045-900 Rio de Janeiro, Brazil; and 2 Departamento de Fisiologia e Farmacologia, Instituto Biomédico, Universidade Federal Fluminense, 24210-130 Niterói, Rio de Janeiro, Brazil
Submitted 28 August 2003
; accepted in final form 12 April 2004
Exercise training is known to improve vasodilating mechanisms mediated by endothelium-dependent relaxing factors in the cardiac and skeletal muscle vascular beds. However, the effects of exercise training on visceral vascular reactivity, including the renal circulation, are still unclear. We used the experimental model of the isolated perfused rabbit kidney, which involves both the renal macro- and microcirculation, to test the hypothesis that exercise training improves vasodilator mechanisms in the entire renal circulation. New Zealand White rabbits were pen confined (Sed; n = 24) or treadmill trained (0% grade) for 5 days/wk at a speed of 18 m/min during 60 min over a 12-wk period (ExT; n = 24). Kidneys isolated from Sed and ExT rabbits were continuously perfused in a nonrecirculating system under conditions of constant flow and precontracted with norepinephrine (NE). We assessed the effects of exercise training on renal vascular reactivity using endothelial-dependent [acetylcholine (ACh) and bradykinin (BK)] and -independent [sodium nitroprusside (SNP)] vasodilators. ACh induced marked and dose-related vasodilator responses in kidneys from Sed rabbits, the reduction in perfusion pressure reaching 41 ± 8% ( n = 6; P < 0.05). In the kidneys from ExT rabbits, vasodilation induced by ACh was significantly enhanced to 54 ± 6% ( n = 6; P < 0.05). In contrast, BK-induced renal vasodilation was not enhanced by training [19 ± 8 and 13 ± 4% reduction in perfusion pressure for Sed and ExT rabbits, respectively ( n = 6; P > 0.05)]. Continuous perfusion of isolated kidneys from ExT animals with N -nitro- L -arginine methyl ester ( L -NAME; 300 µM), an inhibitor of nitric oxide (NO) biosynthesis, completely blunted the additional vasodilation elicited by ACh [reduction in perfusion pressure of 54 ± 6 and 38 ± 5% for ExT and L -NAME + ExT, respectively ( n = 6; P < 0.05)]. On the other hand, L -NAME infusion did not affect ACh-induced vasodilation in Sed animals. Exercise training also increased renal vasodilation induced by SNP [36 ± 7 and 45 ± 10% reduction in perfusion pressure for Sed and ExT rabbits, respectively ( n = 6; P < 0.05)]. It is concluded that exercise training alters the rabbit kidney vascular reactivity, enhancing endothelium-dependent and -independent renal vasodilation. This effect seems to be related not only to an increased bioavailability of NO but also to the enhanced responsiveness of the renal vascular smooth muscle to NO.
chronic exercise; endothelial dysfunction; isolated perfused rabbit kidney
Address for reprint requests and other correspondence: E. Tibiriçá, Departamento de Fisiologia e FarmacodinÂmica, Instituto Oswaldo Cruz, FIOCRUZ, Av. Brasil 4365-Manguinhos, C.P. 926, 21045-900 Rio de Janeiro, RJ, Brazil (E-mail: etibi{at}ioc.fiocruz.br ).