title: Different tolerance to hypothermia and rewarming of isolated rat and guinea pig hearts.
abstract: We examined the effect of hypothermia and rewarming on myocardial function and calcium control in Langendorff-perfused hearts from rat and guinea pig. Both rat and guinea pig hearts demonstrated a rise in myocardial calcium ([Ca]total) in response to hypothermic perfusion (40 min, 10 degrees C), which was accompanied by an increase in left ventricular end diastolic pressure (LVEDP). The elevation in [Ca]total was severalfold higher in guinea pig than in rat hearts, reaching 12.9 +/- 0.8 and 3.1 +/- 0.6 micromol.g dry wt-1, respectively. The rise in LVEDP, however, was comparable in the two species: 62.5 +/- 2.5 (guinea pig) and 52.5 +/- 5.1 mm Hg (rat). Following rewarming, [Ca]total remained elevated in guinea pig, whereas a moderate decline in [Ca]total was observed in the rat (13.6 +/- 1.9 and 2.2 +/- 0.3 micromol.g dry wt-1, respectively). Posthypothermic values of LVEDP were also significantly higher in guinea pig compared to rat hearts (42.5 +/- 6.8 vs 20.5 +/- 5.1 mm Hg, P < 0.027). Furthermore, whereas rat hearts demonstrated a 78 +/- 7% recovery of left ventricular developed pressure, there was only a 15 +/- 7% recovery in guinea pig hearts. Measurements of tissue levels of high energy phosphates and glycogen utilization indicated a higher metabolic requirement in guinea pig than in rat hearts in order to oppose the hypothermia-induced calcium load. Thus, we conclude that isolated guinea pig hearts are more sensitive to a hypothermic insult than rat hearts.
mesh_terms: D000255:Adenosine Triphosphate / Q000378:metabolism; D000818:Animals; D001794:Blood Pressure; D002118:Calcium / Q000378:metabolism; D003080:Cold Temperature; D005260:Female; D006003:Glycogen / Q000378:metabolism; D006168:Guinea Pigs; D006321:Heart / Q000502:physiology; D066298:In Vitro Techniques; D019344:Lactic Acid / Q000378:metabolism; D008297:Male; D009200:Myocardial Contraction; D009206:Myocardium / Q000378:metabolism; D009926:Organ Preservation / Q000379:methods*; D010477:Perfusion; D010725:Phosphocreatine / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley; D013045:Species Specificity