Intercellular communication: role of gap junctions in establishing the pattern of ATP-elicited Ca2+ oscillations and Ca2+-dependent currents in freshly isolated aortic smooth muscle cells.
Cytosolic-free [Ca2+] was evaluated in freshly dissociated smooth muscle cells from mouse thoracic aorta by the ratio of Fura Red and Fluo 4 emitted fluorescence using confocal microscopy. The role of intercellular communication in forming and shaping ATP-elicited responses was demonstrated. Extracellular ATP (250 microM) elicited [Ca2+]i transient responses, sustained [Ca2+]i rise, periodic [Ca2+]i oscillations and aperiodic repetitive [Ca2+]i transients. Quantity of smooth muscle cells in the preparation responding to ATP with periodical [Ca2+]i oscillations depended on the density of isolated cells on the cover slip. ATP-elicited bursts of [Ca2+]i spikes in 66+/-7% of cells in dense and in 33+/-8.5% of cells in non-dense preparations. The number of cells responding to ATP with bursts of [Ca2+]i spikes decreased from 55+/-5% (n=84) to 14+/-3% (n=141) in dense preparations pretreated with carbenoxolone. Simultaneous measurement of [Ca2+]i and ion currents revealed a correlation between [Ca2+]i and current oscillations. ATP-elicited bursts of current spikes in 76% of cells regrouped in small clusters and in 9% of isolated cells. Clustered cells responding to ATP with current oscillations had higher membrane capacity than clustered cells with transient and sustained ATP-elicited responses. Lucifer Yellow (1% in 130 mM KCl) injected into one of clustered cells was transferred to the neighboring cell only when ATP-elicited oscillations. Fast application of carbenoxolone (100 microM) inhibited ATP (250 microM) elicited Ca2+-dependent current oscillations. Taken together these results suggest that the probability of ATP (250 microM) triggered cytosolic [Ca2+]i oscillations accompanied with K+ and Cl- current oscillations increased with the coupling of smooth muscle cells.
Fanchaouy
M
M
Department of Zoology and Animal Biology, University of Geneva, CH-1211 Geneva 4, Switzerland.
Serir
K
K
Meister
J J
JJ
Beny
J L
JL
Bychkov
R
R
D000200:Action Potentials / Q000187:drug effects / Q000502:physiology; D000255:Adenosine Triphosphate / Q000378:metabolism* / Q000494:pharmacology; D000818:Animals; D000897:Anti-Ulcer Agents / Q000494:pharmacology; D001011:Aorta / Q000166:cytology / Q000187:drug effects / Q000502:physiology; D001683:Biological Clocks / Q000187:drug effects / Q000502:physiology; D002118:Calcium / Q000378:metabolism; D015220:Calcium Channels / Q000187:drug effects / Q000502:physiology; D020013:Calcium Signaling / Q000187:drug effects / Q000502:physiology*; D002229:Carbenoxolone / Q000494:pharmacology; D002450:Cell Communication / Q000502:physiology*; D002452:Cell Count; D002478:Cells, Cultured; D018118:Chloride Channels / Q000187:drug effects / Q000502:physiology; D017629:Gap Junctions / Q000187:drug effects / Q000502:physiology*; D007546:Isoquinolines; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D009119:Muscle Contraction / Q000187:drug effects / Q000502:physiology; D032389:Myocytes, Smooth Muscle / Q000187:drug effects / Q000502:physiology*; D018408:Patch-Clamp Techniques; D015221:Potassium Channels / Q000187:drug effects / Q000502:physiology
D000897:Anti-Ulcer Agents; D015220:Calcium Channels; D018118:Chloride Channels; D007546:Isoquinolines; D015221:Potassium Channels; D000255:Adenosine Triphosphate; C017475:lucifer yellow; D002229:Carbenoxolone; D002118:Calcium