Key result
Ovariectomy significantly increased peak [Ca2+]i and the amplitude of the Ca2+ transient in female rat cardiac myocytes compared with sham and 17beta-oestradiol-replaced animals (P<0.01).
Why the study?
Does 17beta-oestradiol replacement reverse the effects of ovariectomy on intracellular calcium dynamics in female rat cardiac myocytes?
Does 17beta-oestradiol replacement reverse the effects of ovariectomy on intracellular calcium dynamics in female rat cardiac myocytes?
p-value: p=<0.01
Oestrogen appears to play a long-term role in limiting calcium entry into cardiac myocytes, as ovariectomy increases peak intracellular calcium and transient amplitude, which is reversed by 17beta-oestradiol replacement.
Hypothesis-generating for oestrogen's role in myocyte calcium handling; leaves open clinical translation pending human data.
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.
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Curl et al. (2003) studied Ovariectomy and estrogen replacement effects on cardiac myocytes. 17beta-oestradiol replacement vs. Sham and OVX alone was evaluated on Peak [Ca2+]i and amplitude of the Ca2+ transient (p=<0.01). Ovariectomy significantly increased peak [Ca2+]i and the amplitude of the Ca2+ transient in female rat cardiac myocytes compared with sham and 17beta-oestradiol-replaced animals (P<0.01).
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