Functional characteristics and responses to adrenergic stimulation of isolated heart preparations from hypothermic and hibernating subjects

Negative inotropic effects of epinephrine in the presence of increased β-adrenoceptor sensitivity during hypothermia in a rat model

“…This is supported by studies showing that reduced core temperature induces a decline in cytochrome P450 activity and other important enzymes for drug elimination [37]. During normal core temperatures, the b-adrenoceptor agonists Epi and isoproterenol mediate inotropic effects via the sarcolemmal G-protein -protein kinase A (PKA) signaling pathway, by increasing intracellular cyclic adenosine monophosphate (cAMP) levels [7,10]. During cooling below 34°C, the inotropic effect of Epi has been reported to decrease [30].…”

“…Both the American [34] and European guidelines [27] for cardiac support of patients during rewarming from accidental hypothermia do however state that use of drugs like epinephrine http://dx.doi.org/10.1016/j.cryobiol.2014. 10.012 0011-2240/Ó 2014 Elsevier Inc. All rights reserved.…”

Mammalian Hibernation: An Escape from the Cold

“…Studies on the isolated, perfused heart indicate that hearts from species which hibernate (body temperature = 2 0 -7 °C typically, e. g., woodchuck, ground squirrel, chipmunk, and hamster) continue to beat at -0.5 0 to 7°C, whereas hearts from those which do not hibernate (tree squirrel, white rat, cotton rat, and mountain beaver) stop beating at 10 0 to 16°C (Lyman and Blinks 1959). The left ventricular pressure is maintained between 70 and 110 mmHg and between 22 0 and 6°C and the autoregulated coronary flow remains constant down to 6°C in the isolated, perfused heart of the golden hamster (Jones and Romano 1984). In the 13-lined ground squirrel, the autoregulation of coronary flow and the cardiac output of isolated working heart persist down to at least 7°C but both are abolished in the rat below 17°C (Burlington et al 1986).…”

Physiological Society Symposium – Vagal Control: From Axolotl to Man

“…In several studies, administration of adrenergic agonists to animals in steadystate hibernation or hearts isolated from animals in hibernation increased heart rate and these effects were blocked by p-adrenoreceptor antagonists (e.g. propranolol) (Twente & Twente, 1978;Jones & Romano, 1984;Senturia et at. 1986).…”

“…Heart rate, breathing frequency and metabolic rate peak in mid to late arousal, coincident with peaks in the demands of shivering and non-shivering thermogenesis. Once body temperature starts to rise, sympathetic tone is slowly withdrawn and the sensitivity of the heart to sympathetic and vagal influences increases until normal autonomic balance is restored and body temperature attains euthermic levels (Twente & Twente, 1978;Jones & Romano, 1984;Senturia et al 1986;Burlington & Milsom, 1989).…”