Contraction and intracellular Ca2+ in ventricular myocytes from rats receiving fructose-enriched diets

ABSTRACT

Contraction and intracellular Ca2+ in ventricular myocytes from rats receiving fructose-enriched diets [FED] were investigated. Groups of male Wistar rats received normal rat chow together with either normal drinking water or water containing 500 mM fructose ad libitum. Experiments were performed 12-14 weeks later. Rats receiving FED responded differently to a st and ard glucose tolerance test. Fasting blood glucose levels in FED and control rats were 48.5 +/- 2.3 [4] and 47.0 +/- 1.9 [4] mg/dl, respectively. At 30 min after intraperitoneal administration of glucose [2g/kg body weight], concentrations of blood glucose were significantly [p<0.05] higher in rats receiving FED [206.3 +/- 19.5 mg/dl] compared to controls [150.3 +/- 8.5 mg/dl]. At 120 min, blood glucose in FED [87.3 +/- 4.2] and control [80.3 +/- 3.4 mg/dl] rats were still significantly [p<0.01] higher than initial values. Amplitude and time to half [THALF] relaxation of ventricular myocyte shortening and Ca2+ transient were not altered by FED. Time to peak [TPK] shortening was unaltered, however, the TPK Ca2+ transient was significantly prolonged in FED rats [65.1 +/- 3.4 ms] compared to controls [56.4 +/- 2.0 ms]. In conclusion, diets supplemented with drinking water containing 500 mM fructose for a period of 12-14 weeks did not have significant effects on ventricular myocyte shortening but did prolong the time course of the Ca@@@@@@ transient suggesting that defects in Ca2+ transport may precede defects in myocyte contractility in this experimental model