Fig. 1.

Simultaneous in situ measurements of intracellular free Ca²⁺ concentration ([Ca²⁺]_i) and nitric oxide (NO) levels in individual cells of intact uterine artery endothelium (UA Endo). A: representative 4,5-diaminofluorescein (DAF-2) fluorescence image taken at an excitation wavelength (λ) of 485 nm and an emission λ of 535 nm after incubation under control conditions (left) or with ATP (100 uM; right) for 25 min. B: representative simultaneous recordings of ATP-induced increase in [Ca²⁺]_i and DAF-2 fluorescence from a single intact endothelial cell of UA Endo from luteal (top) and pregnant ewes (bottom). Note the upper response shows a single [Ca²⁺]_i peak (burst), while the lower shows 3 clear successive [Ca²⁺]_i bursts. C: conversion of relative DAF-2 fluorescence (F/F0) to rate increase of DAF-2 fluorescence, thus providing a measure of endothelial NO synthase (eNOS) activity with time.