Assuntos
Tolerância ao Trabalho Programado/psicologia , Adaptação Fisiológica , Adaptação Psicológica/fisiologia , Adulto , Clima Frio , Combustíveis Fósseis , Humanos , Masculino , Pessoa de Meia-Idade , Personalidade/fisiologia , Petróleo , Psicofisiologia , Fatores de Tempo , U.R.S.S. , Tolerância ao Trabalho Programado/fisiologiaRESUMO
In white rats both adapted and unadapted to cold and in lemmings the total heat production and skeletal muscles contractile activity under noradrenaline and propranolol were estimated at different ambient temperatures. In rats, the regulatory and adaptive changes of heat production occur due to a significant extension of adrenergically modulated part of contractile thermal effect in muscles, as well as to increased nonshivering thermogenesis. In lemmings, the adaptability to cold is maintained chiefly by nonshivering thermogenesis and leads to no alterations in muscle energetics.
Assuntos
Aclimatação/efeitos dos fármacos , Arvicolinae/fisiologia , Regulação da Temperatura Corporal/efeitos dos fármacos , Temperatura Baixa , Norepinefrina/farmacologia , Propranolol/farmacologia , Animais , Eletromiografia , Contração Muscular/efeitos dos fármacos , Consumo de Oxigênio/efeitos dos fármacos , Ratos , Especificidade da EspécieRESUMO
Siberian lemmings seem to have lesser noradrenaline (NA) calorigenic action and higher beta-adrenergic "asymmetry" of catecholamine calorigenic effects than the cold- and warmth-adapted laboratory rodents. Selective inhibition of catecholamine effects by beta-adrenoblocking drug propranolol, obvious potentiation of NA effect by caffeine, and compensatory increasing of thermoregulatory musclar contractile activity during the blockade of betaadrenoreceptors under cooling suggest the domineering of betaadrenergic mechanisms of thermogenesis in siberian lemmings and their high thermoregulatory lability.
Assuntos
Regulação da Temperatura Corporal , Roedores/fisiologia , Sistema Nervoso Simpático/fisiologia , Animais , Temperatura Corporal/efeitos dos fármacos , Regulação da Temperatura Corporal/efeitos dos fármacos , Cafeína/farmacologia , Interações Medicamentosas , Isoproterenol/farmacologia , Norepinefrina/farmacologia , Consumo de Oxigênio/efeitos dos fármacos , Propranolol/farmacologia , Receptores Adrenérgicos beta/efeitos dos fármacos , Receptores Adrenérgicos beta/fisiologiaRESUMO
The administration of beta-adrenergic blocking agent propranolol to cold adapted rats entailed some decrease of the total metabolic reaction and body temperature as well as an additive (compensatory) increase of electrical muscle activity. The compensatory effect was more obvious in postural-tonic groups of muscles (m. trapezius, m. masseter) and in deeper portions of muscles (m. tibialis ant., m. trapezius), mainly presented by the red fibers. An adaptive increase of non-shivering thermogenesis and temperature effect of muscular contraction seem to be mainly controlled by beta-adrenergic mechanisms.
