abstract
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The objective of this work was to confirm that the contractile effects of ouabain and Na -free solutions in guinea pig tracheal rings are associated with increments in the cytosolic free Ca2 concentration ([Ca2 ]i) in cultured tracheal smooth muscle (TSM) cells. Cultured cells were α-actin positive. Histamine (50 μM) and Na - free solution elicited a transient increase in [Ca2 ]i, while the responses to thapsigargin (1 μM) and ouabain (I mM) were long lasting. However, carbachol (10, 200, and 500 mM) and high K -solution produced no effect on [Ca2 ]i, suggesting that cultured guinea pig TSM cells display a phenotype change but maintain some of the tracheal rings physiological properties. The transient rise in [Ca2 ]i in response to the absence of extracellular Na and the effect of ouabain may indicate the participation of the Na /Ca2 exchanger (NCX) in the regulation of [Ca2 ]i.
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The objective of this work was to confirm that the contractile effects of ouabain and Na%2b-free solutions in guinea pig tracheal rings are associated with increments in the cytosolic free Ca2%2b concentration ([Ca2%2b]i) in cultured tracheal smooth muscle (TSM) cells. Cultured cells were α-actin positive. Histamine (50 μM) and Na%2b- free solution elicited a transient increase in [Ca2%2b]i, while the responses to thapsigargin (1 μM) and ouabain (I mM) were long lasting. However, carbachol (10, 200, and 500 mM) and high K%2b-solution produced no effect on [Ca2%2b]i, suggesting that cultured guinea pig TSM cells display a phenotype change but maintain some of the tracheal rings physiological properties. The transient rise in [Ca2%2b]i in response to the absence of extracellular Na%2b and the effect of ouabain may indicate the participation of the Na%2b/Ca2%2b exchanger (NCX) in the regulation of [Ca2%2b]i.
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