Responses to exercise, fluid, and energy balances during Ramadan in sedentary and active males.

This study compares the effects of the Ramadan fast (RF) on body and plasma compositions, hematology, and responses to steady state submaximal exercise in six physically active (A, 35.5+/-1.6 y) and seven sedentary (S, 37.

Ischemic preconditioning is not additive to preservation with hypothermia or crystalloid cardioplegia in the globally ischemic rat heart.

The aim of this study was to evaluate the additive protective efficiency of ischemic preconditioning when used in combination with conventional clinically relevant cardioprotective methods of hypothermia or hypothermic cardioplegia during sustained global ischemia. Isolated rat hearts were aorta-perfused with Krebs-Henseleit buffer and were divided into six groups (n = 10 each). Group I: Ischemia at 34 degrees C for 60 min; Group PC + I: preconditioned (PC) ischemia at 34 degrees C, 2 episodes of 5 min ischemia and 10 min reperfusion at 34 degrees C followed by I; Group HI: hypothermic ischemia at 10 degrees C for 60 min; Group PC + HI: preconditioned (PC) hypothermic ischemia, 2 episodes of 5 min ischemia and 10 min reperfusion at 34 degrees C followed by HI; Group CPL + HI: single dose of 'Plegisol' cardioplegia followed by HI; Group PC + CPL + HI: preconditioned hypothermic cardioplegia, followed by CPL + HI.

Inotropic effects of ionic and nonionic contrast materials in isolated heart preparations.

The inotropic effects of ionic (amidotriazoate) and nonionic (iohexol) contrast material were compared in isolated rat heart preparations. Left atria exposed to amidotriazoate for 10 mins exhibited a dose dependent depression of contractile force approximately twice as large as that brought about by equiosmolar sucrose. When the driving rate was reduced from 60 to 20 beats/min, this specific effect was abolished.

Differences in electrical and mechanical recovery from ischemic heart arrest and cardioplegia.

The course of recovery of heart activity [assessed by heart rate, atrioventricular (AV) conduction time, monophasic action potentials, contractile force, and perfusion rate] from hypothermic ischemic arrest was studied on isolated perfused rat hearts. The effect of control ischemic arrest was compared with various cardioplegic protective formulations based on high K+ content. During control hypothermic ischemia (20 degrees C), the heart activity extinguished only gradually, action potentials were biphasic, AV conduction was extremely prolonged, and contractions were slow and relatively strong.