Histamine-induced Calcium Released from Cultured Human Mucosal Microvascular Endothelial Cells from Nasal Inferior Turbinate

Abstract

Changes in cytosolic Ca²⁺ concentration ([Ca²⁺],) in cultured human mucosal microvascular endothelial cells (HM-MECs) from nasal inferior turbinate were measured using a fluorescent Ca²⁺-sensitive dye, fura-2, and photometric fluorescence microscopy. Histamine caused a transient increase in intracellular free Ca²⁺ in cell populations and in individual cells, followed by a decrease to a sustained elevation. Histamine (100 μ) elevated [Ca³⁺]_i in HMMECs up to 563 ± 20 nM from a resting level of 60 ± 45 nM (means ± SD, n = 31). Promethazine (a histamine H, receptor antagonist) inhibited [Ca²⁺] increase during histamine stimulation, whereas cimetidine (a H₂ receptor antagonist) and thioperamide (a H, receptor antagonist) showed no inhibition. These results suggest that the histamine increase [Ca²⁺]_i in HMMECs induces both a Ca²⁺ release from stores and a Ca²⁺ influx through activation of the H, receptor.

Key Words:

• human mucosal microvascular endothelial cells
• histamine
• fura-2
• histamine receptor
• nasal allergy
• vascular permeability