Acta Physiologica 2011; Volume 202, Supplement 684
The Joint Conference (FAMÉ 2011) of the LXXVth Meeting of the Hungarian Physiological Society, XVIth Meeting of the Hungarian Society of Anatomists, Experimental Section of the Hungarian Society for Experimental and Clinical Pharmacology and Hungarian Society for Microcirculation and Vascular Biology
DEPRESSED CALCIUM CYCLING CONTRIBUTES TO LOWER ISCHEMIA TOLERANCE IN HEARTS OF OVARIECTOMIZED RATS
Abstract number: P66
Paragi1 P., Sara L., Dunay1 G., Vakaliosz1 A., Rozsits1 A., Acs2 N., Ivanics1 T., Miklos1 Zs.
The cardioprotectiveeffects of estrogens may be recognized by their beneficial influence on cardiac intracellular calcium(Ca2+i) handling. However, literature data supporting this hypothesis are scarce. We aimed to show a relationship between ovariectomy and Ca2+i-cycling and detect its effects on ischemic tolerance.
Isolated Langendorff-perfused hearts of ovariectomized (OVX) and control female rats were studied 10 weeks after operation. A subset of the animals received estrogen replacement therapy (ERT) (estradiol propionate 450 mg/bwkg/week im.). Left ventricular pressure, coronary flow, and, using Indo-1, surface fluorometry Ca2+i-transients were recorded. Hearts were exposed to 30 min global ischemia followed by 30 min reperfusion.
Hemodynamic performance of isolated hearts was similar in all studied groups under resting conditions. Analysis of Ca2+i-transients revealed depressed Ca2+ sequestration in the OVX group which was restored by ERT. Lower ischemia tolerance following OVX was evidenced by more pronounced ischemic contracture and slower restitution of contractile/lusitropic function during reperfusion. Ca2+i-handling of OVX hearts was characterized by higher [Ca2+i]duringischemia. The onset of reperfusion resulted in a sudden elevation of basal [Ca2+i]. In hearts of OVX rats basal [Ca2+i] increase was higher and restitution of the rate of Ca2+ release and sequestration was slower during reperfusion. Depressed ischemic tolerance of OVX hearts was restored by ERT regarding both hemodynamic and Ca2+i-handling parameters.
Ovariectomy produced depressed cardiac Ca2+i-cycling which aggravated the impairment of Ca2+i-handling during ischemia/reperfusion contributing to lower cardiac ischemia tolerance. Consequently, estrogens may exert their cardioprotective effects by protecting cardiac Ca2+i-homeostasis.
OTKA grant 68502
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Acta Physiologica 2011; Volume 202, Supplement 684 :P66