Aimin Zhang¹, Bella T. Altura^2,3 and Burton M. Altura^1,2,3

Departments of ¹Physiology and ²Medicine, and ³The Center for Cardiovascular and Muscle Research, State University of New York, Health Science Center at Brooklyn, NY 11203

Received 5/15/97; Accepted 5/21/97; On-line 6/1/97

4. RESULTS

With 1.2 mM extracellular Mg²⁺ activity, the basal level of [Mg²⁺]_i in human aortic endothelial cells, estimated from the ratio (F340/ F380), is 0.51±0.04 mM, ranging between 0.45 mM and 0.57 mM (Table 1). The distribution of [Mg²⁺]_i was heterogeneous, i.e., there were "hot" areas of [Mg²⁺]_i, referred to as intensive brightness spots which were scattered among the cells, and around these were weak brightness spots, areas with very low [Mg²⁺]_i. Increasing [Mg²⁺]_o to 4.8 mM Mg²⁺ caused about a 60% significant increase of [Mg²⁺]_i in 2-10 min, from a basal value of 0.51 mM to a mean value of 0.80±0.07 mM (ranging between 0.67 mM to 0.88 mM), while the [Mg²⁺]_i/[Mg²⁺]_o ratio decreased from 0.43±0.01 to 0.16±0.01 (Table 1). The rises of [Mg²⁺]_i were maintained for at least 30 min. Concomitant with the [Mg²⁺]_i elevation, the number and intensity of brightness spots were increased within each endothelial cell.