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Effects of ovariectomy and 17β‐oestradiol replacement on [Ca 2+ ] i in female rat cardiac myocytes
Author(s) -
Curl Claire L,
Wendt Igor R,
Canny Benedict J,
Kotsanas George
Publication year - 2003
Publication title -
clinical and experimental pharmacology and physiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.752
H-Index - 103
eISSN - 1440-1681
pISSN - 0305-1870
DOI - 10.1046/j.1440-1681.2003.03864.x
Subject(s) - endocrinology , medicine , myocyte , collagenase , extracellular , chemistry , calcium , cardiac myocyte , biology , enzyme , biochemistry
Summary 1. The present study investigated the effects of ovariectomy (OVX) and 17β‐oestradiol replacement on [Ca 2+ ] i in rat freshly isolated cardiac myocytes. 2. Myocytes were isolated from the hearts of sham, OVX and OVX + 17β‐oestradiol‐replaced female rats by enzymatic digestion with collagenase. Changes in [Ca 2+ ] i in response to varied extracellular [Ca 2+ ] were measured using the Ca 2+ ‐sensitive dye fura‐2, with the contractile responses of each cell measured as cell shortening. 3. Increasing extracellular [Ca 2+ ] resulted in increased [Ca 2+ ] i in all three groups. Peak [Ca 2+ ] i and the amplitude of the Ca 2+ transient were significantly greater ( P < 0.01) in cells from OVX animals compared with cells from both sham and 17β‐oestradiol‐replaced OVX animals. 4. The time‐course of decay of the Ca 2+ transient was significantly faster ( P < 0.02) in OVX cells compared with both sham and 17β‐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 17β‐oestradiol cells. 5. These data demonstrate clear differences in peak [Ca 2+ ] i and the amplitude of the Ca 2+ transient between OVX female rat cardiac myocytes compared with intact and 17β‐oestradiol‐replaced OVX female rat cardiac myocytes. This suggests that oestrogen may play a long‐term role in limiting Ca 2+ entry into the cardiac myocyte.