HISTAMINE‐INDUCED CALCIUM OSCILLATIONS IN HUMAN VASCULAR SMOOTH MUSCLE: TEMPORAL SEQUENCE AND SPATIAL ORGANIZATION IN SINGLE CELLS

Abstract

SUMMARY: 1. Video imaging of single, fura2‐loaded vascular smooth muscle cells was used to examine the spatial and temporal alterations in calcium, Ca²⁺, in response to low levels of vasoconstrictor stimuli.2. Histamine (0.5 μmol/L) produced repetitive oscillations in Ca²⁺, which appeared to show some variation in amplitude and frequency between cells.3. Individual oscillations consisted of an initial increase in Ca²⁺ in a localized region followed by a wave‐like propagation of this region of elevated Ca²⁺ throughout the rest of the cell cytoplasm.4. It is suggested that the subcellular spatial organization of Ca²⁺ that was observed during a Ca²⁺ oscillation allows a population of cells to operate in unison. Thus, oscillatory fluctuations in Ca²⁺ may contribute to myogenic tone.