Key result
PKCα deficiency in mice reduced ET-1-evoked pulmonary vasoconstriction by approximately 40% but led to pulmonary vascular hyperresponsiveness to the TXA2 analog U46619, associated with a 2.7-fold increase in TP receptor expression.
Why the study?
Does PKCα deficiency alter pulmonary vascular responsiveness to vasoconstrictors and acute hypoxia in mice?
Does PKCα deficiency alter pulmonary vascular responsiveness to vasoconstrictors and acute hypoxia in mice?
p-value: p=<0.01
PKCα deficiency in mice reduces ET-1-induced pulmonary vasoconstriction but causes hyperresponsiveness to TXA2, associated with upregulated TP receptor expression.
Pulmonary vascular hyperresponsiveness is a main characteristic of pulmonary arterial hypertension (PAH). In PAH patients, elevated levels of the vasoconstrictors thromboxane A2 (TXA2), endothelin (ET)-1 and serotonin further contribute to pulmonary hypertension. Protein kinase C (PKC) isozyme alpha (PKCα) is a known modulator of smooth muscle cell contraction. However, the effects of PKCα deficiency on pulmonary vasoconstriction have not yet been investigated. Thus, the role of PKCα in pulmonary vascular responsiveness to the TXA2 analog U46619, ET-1, serotonin and acute hypoxia was investigated in isolated lungs of PKCα-/- mice and corresponding wild-type mice, with or without prior administration of the PKC inhibitor bisindolylmaleimide I or Gö6976. mRNA was quantified from microdissected intrapulmonary arteries. We found that broad-spectrum PKC inhibition reduced pulmonary vascular responsiveness to ET-1 and acute hypoxia and, by trend, to U46619. Analogously, selective inhibition of conventional PKC isozymes or PKCα deficiency reduced ET-1-evoked pulmonary vasoconstriction. The pulmonary vasopressor response to serotonin was unaffected by either broad PKC inhibition or PKCα deficiency. Surprisingly, PKCα-/- mice showed pulmonary vascular hyperresponsiveness to U46619 and increased TXA2 receptor (TP receptor) expression in the intrapulmonary arteries. To conclude, PKCα regulates ET-1-induced pulmonary vasoconstriction. However, PKCα deficiency leads to pulmonary vascular hyperresponsiveness to TXA2, possibly via increased pulmonary arterial TP receptor expression.
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Tabeling et al. (2015) studied Pulmonary vascular hyperresponsiveness. PKCα deficiency vs. Wild-type mice was evaluated on Pulmonary vascular responsiveness to ET-1 and U46619 (p=<0.01). PKCα deficiency in mice reduced ET-1-evoked pulmonary vasoconstriction by approximately 40% but led to pulmonary vascular hyperresponsiveness to the TXA2 analog U46619, associated with a 2.7-fold increase in TP receptor expression.
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