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Gender differences in sarcoplasmic reticulum calcium loading after isoproterenol
Jarvis Chen1, John Petranka, Ken Yamamura
1Laboratories of Signal Transduction, National Institute of Environmental Health Sciences, National Institutes of Health, Research Triangle Park, NC 27709, USA.
American Journal of Physiology. Heart and Circulatory Physiology
|August 30, 2003
Summary
Males have higher sarcoplasmic reticulum (SR) Ca2+ levels than females, potentially explaining why women experience less myocardial ischemia-reperfusion injury. This study investigated gender differences in SR Ca2+ handling.
Area of Science:
- Cardiovascular Physiology
- Cellular Biology
- Biochemistry
Background:
- Males exhibit greater myocardial ischemia-reperfusion (I/R) injury than females, particularly under hypercontractile conditions.
- Increased sarcoplasmic reticulum (SR) Ca2+ is implicated in enhanced I/R injury in males.
Purpose of the Study:
- To investigate potential gender differences in SR Ca2+ handling.
- To determine if SR Ca2+ levels correlate with observed gender disparities in myocardial I/R injury.
Main Methods:
- Utilized NMR Ca2+ indicator (1,2-bis(2-amino-5,6-difluorophenoxy)-ethane-N,N,N',N'-tetraacetic acid) to measure SR Ca2+ in perfused rabbit hearts.
- Measured caffeine-induced SR Ca2+ release in isolated ventricular myocytes using fura-2.
- Investigated the role of nitric oxide synthase (NOS) by treating female myocytes with NG-nitro-l-arginine methyl ester.
Main Results:
- Male hearts showed significantly higher SR Ca2+ levels after isoproterenol treatment compared to female hearts.
- Isolated male myocytes released more Ca2+ from the SR after caffeine stimulation than female myocytes, especially after isoproterenol treatment.
- Inhibiting NOS in female myocytes increased SR Ca2+ release to levels comparable to males, and female myocytes exhibited higher neuronal NOS levels.
Conclusions:
- Significant gender differences exist in SR Ca2+ handling, with males exhibiting higher SR Ca2+ levels.
- These differences in SR Ca2+ regulation, potentially influenced by NOS activity, may underlie the reduced myocardial I/R injury observed in females.