Effects of ovariectomy and 17 beta-oestradiol replacement on [Ca2+]i in female rat cardiac myocytes.
1. The present study investigated the effects of ovariectomy (OVX) and 17beta-oestradiol replacement on [Ca2+]i in rat freshly isolated cardiac myocytes. 2. Myocytes were isolated from the hearts of sham, OVX and OVX + 17beta-oestradiol-replaced female rats by enzymatic digestion with collagenase. Changes in [Ca2+]i in response to varied extracellular [Ca2+] were measured using the Ca2+-sensitive dye fura-2, with the contractile responses of each cell measured as cell shortening. 3. Increasing extracellular [Ca2+] resulted in increased [Ca2+]i in all three groups. Peak [Ca2+]i and the amplitude of the Ca2+ transient were significantly greater (P < 0.01) in cells from OVX animals compared with cells from both sham and 17beta-oestradiol-replaced OVX animals. 4. The time-course of decay of the Ca2+ transient was significantly faster (P < 0.02) in OVX cells compared with both sham and 17beta-oestradiol-replaced cells. In addition, time to 50% relaxation was significantly faster (P < 0.04) and extent of shortening significantly greater (P < 0.01) in OVX cells than in either sham or 17beta-oestradiol cells. 5. These data demonstrate clear differences in peak [Ca2+]i and the amplitude of the Ca2+ transient between OVX female rat cardiac myocytes compared with intact and 17beta-oestradiol-replaced OVX female rat cardiac myocytes. This suggests that oestrogen may play a long-term role in limiting Ca2+ entry into the cardiac myocyte.
Curl
Claire L
CL
Department of Physiology, Monash University, Melbourne, Victoria, Australia.
Wendt
Igor R
IR
Canny
Benedict J
BJ
Kotsanas
George
G
D000818:Animals; D002118:Calcium / Q000378:metabolism* / Q000494:pharmacology; D004305:Dose-Response Relationship, Drug; D004958:Estradiol / Q000494:pharmacology*; D045604:Extracellular Fluid / Q000187:drug effects / Q000378:metabolism; D005260:Female; D032383:Myocytes, Cardiac / Q000187:drug effects* / Q000378:metabolism; D010052:Ovariectomy / Q000379:methods*; D051381:Rats; D017208:Rats, Wistar
D004958:Estradiol; D002118:Calcium