RESUMEN
Fasting and calorie restriction have some Cardioprotective effects. In view of the effect of fasting on peripheral benzodiazepine receptors and widespread administration of benzodiazepines in medicine, the present study was designed to evaluate whether fasting may affect myocardial vulnerability to cardiac ischemia-reperfusion [I/R] following repeated diazepam administration. Rats were divided into six groups of 8 or 10 animals. Groups I and II were controls which received intra peritoneal injection of normal saline solution for 5 days. Also, Control II underwent fasting on 5th day of experiment. Four test groups received intra peritoneal injection of diazepam for 5 days [groups I and II Img/kg; groups III and IV 5 mg/kg]. Also, test groups II and IV fasted on 5th day of experiment. The Langendorff isolated hearts were subjected to 25 minutes ischemia and 25 minutes reperfusion. Cardiac parameters including - left ventricular developed pressure and rate pressure product were determined. Infarct size was measured by Triphenyltetrazolium staining. Recovery of the left ventricular developed pressure in diazepam groups were significantly lower than control I and II [P=0.049 and P=0.046 respectively]. But there was no significant difference among the controls and test group II, which fasted following diazepam administration. This showed the preservation of the cardiac performance in the fasting animals following administration of diazepam [1 mg/kg]. The results obtained showed the exacerbation of ischemia reperfusion injury in the presence of diazepam and demonstrated the protective effect of fasting which is probably due to modulation of the mitochondrial permeability transition pore
RESUMEN
To investigate the effects of acetazolamide on the ischemia-reperfused isolated hearts of 2- and 8-week-old rabbits. This study was conducted at the Kermanshah Medical Biology Research Center, Kermanshah, Iran from March to September 2011. Two- [n=17] and 8-week old [n=17] rabbits were separately divided into 2 control [n=9], and test [n=8] groups. Isolated hearts were subjected to 35 minutes ischemia and 30 minutes reperfusion. Acetazolamide [100 microgr/l] was added to the perfusion solution for 10 minutes before ischemia in the test group. Cardiac parameters including ventricular pressure, heart rate [HR], and rate pressure product [RPP] were measured. Data sets were analyzed by t-test. Following acetazolamide administration the change percentage of HR was significantly different in the 2-week [91 +/- 1.1%] compared with the 8- week [96 +/- 0.8%] test groups [p=0.0016]. Recovery percentage of RPP in reperfusion was lower [p=0.005] in the 8- [28.9 +/- 3.4%] than the 2-week test groups [45.2 +/- 3.5%]. The 2-week hearts elicited more rapid response to carbonic anhydrase [CA] inhibition than the 8-week group. However, acetazolamide does not exacerbate ischemia-reperfusion [I/R] injury in the 2-week hearts. Therefore, it was revealed that after inhibition of CA, the age dependent pattern of I/ R injury was similar to that of the normal hearts. Inspite of the CA important role in the normal heart function, it is not a determining factor in I/R injury in different ages