Tissues changes in FA metabolism can occur quite rapidly in response to
ischemia and may require immediate microwave fixation to determine basal concentrations. The present study aimed to quantify the effects of immediate no-flow
ischemia on concentrations of individual nonesterified FA (
NEFA) and
acyl-CoA species in the rat heart. Male CDF 344 rats were anesthetized and decapitated either 5 min prior to being microwaved (5.5 kW, 3.4 s, twice) to produce
ischemia or microwaved prior to
decapitation (nonischemic). Hearts were then removed and used to measure the concentrations of
acyl-CoA species and FA in several
lipid classes. The ischemic heart total
NEFA concentration was significantly lower than that in the nonischemic heart (11.9 vs. 19.0 nmol/g). Several individual
NEFA concentrations were decreased by 31-85%. Ischemic heart total
long-chain acyl-CoA concentrations (21.0 nmol/g) were significantly higher than those in nonischemic hearts (11.4 nmol/g). Increased concentrations of individual
acyl-CoA species occurred in
palmitoyl-CoA,
stearoyl-CoA,
oleoyl-CoA, and
linoleoyl-CoA. Concentrations of short-chain
acetyl-CoA and beta-hydroxy-beta-methylglutaryl-
CoA were also two- to three-fold higher in ischemic hearts than in nonischemic hearts. The FA concentration in TG and
phospholipids generally did not differ between the groups. Decreases in concentrations of individual FA and increases in
acyl-CoA species during no-flow
ischemia occur very rapidly within the heart. Although it is not clear how these alterations contribute to the pathogenesis of
ischemia, it is evident that future studies attempting to quantify basal levels of these metabolites could use microwave fixation.