Maternal Microvascular Calcium Sparks Are Reduced in Preeclampsia.

Reduced Ca2+ spark frequency in pressurized omental resistance arteries from women with preeclampsia is linked to lower spontaneous transient outward currents and impaired sarcoplasmic reticulum Ca2+ handling.

• Why it matters: Microvascular dysfunction drives hypertensive pregnancy complications, but the Ca2+ sparks–BKCa mechanism underlying preeclampsia has not been defined.
• What they did: Omental arteries from normotensive pregnant women and women with preeclampsia were imaged (20–110 mm Hg) for Ca2+ sparks and caffeine-evoked release (10 mmol/L; 80 mm Hg), while smooth muscle cells were tested for transient outward and BKCa currents; SERCA2 and PLN proteoforms were quantified by LC-SRM/MS.
• The result: Preeclampsia showed reduced Ca2+ spark frequency (P=1.1×10−10) and transient outward current frequency (P=0.023), plus decreased caffeine-evoked release (P=0.0013) and refilling (P=2.0×10−4) with a lower SERCA2-to-unphosphorylated PLN ratio (P=0.030); HBD2 (0.01–10 nmol/L) induced BKCa-dependent relaxation (P=4.6×10−10) without changing Ca2+ spark frequency.

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