Expression of heat shock proteins in turtle and mammalian hearts: Relationship to anoxia tolerance
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Heat shock proteins may plav a cardioproteclive role during hypoxia or ischemia We hypothesized that cardiac tissue from highly hypoxia tolerant animals might superexpress specific HSPs either by induction or constitutively We measured myocardial HSP60 and HSP72/73 in painted and softshelled turtles during normoxia, anoxia (12 h), and after recovery (12 or 24 h). We also measured myocardial HSPs in normoxic rats and rabbits During normoxia, hearts from the most highly anoxia tolerant species, the painted tunic, expressed the highest levels of HSP60 (22.66.0 mg/g total protein) followed b> softshells (11.52.1), rabbits (8.711.0) and rats (3.9+1.1). HSP72/73 levels, however, were not significantly different. Painted turtle HSP60 increased slightly after 12 h of anoxia (P>0.()5 ). It then decreased to below normoxic levels after 12 h of recovery and remained at this lower level through 24 h. This level was lower than the maximum anoxic alue (PO.05). Myocardial HSP60 levels in softshelled turtles did not deviate significantly from control under all experimental conditions. The pattern of changes observed in HSP72/73 were quite different in our two turtle species. In painted turtles anoxia induced a significant increase in myocardial HSP72/73 (from 2 80.4 mg/g normoxic to 3 9tO +>) By 12 h of recovery. HSP72/73 had returned to control levels and remained there through 24 h. In softshelled turtles, HSP72/73 decreased significantly after 12 h of anoxia (from 2.4+1.0 rng/g normoxic to I.IKU). 12 h ofrecocry saw a return of HSP72/7T levels io control. HSP72/7.1 rose to significantly above control after 24 h of recover, (4.1 j 1 ' mg/g). Our data support our hpothesis for HSP60 but not for HSP72/73 We also conclude that anoxia tolerant and anoxia sensitive turtles exhibit different patterns 01 myocardial HSP changes during anoxia and recovery Whether these changes correlate with their relative degrees of anoxia tolerance remains to be determined Supported by NIH HL-45257 and HL-W510.
