Postnatal maturational shift from PKCzeta and voltage-gated K+ channels to RhoA/Rho kinase in pulmonary vasoconstriction.
OBJECTIVE
The neonate is at high risk of developing pulmonary hypertension, which may reflect a misbalance between vasodilator and vasoconstrictor agents. Thromboxane A(2) (TXA(2)) is involved in several forms pulmonary hypertension, but the signaling pathways mediating its pulmonary vasoconstrictor responses during postnatal maturation have not been analyzed. We therefore investigated the role of L-type Ca(2+) channels, protein kinase C (PKC) zeta, voltage-gated K(+) channels (K(V)), and RhoA/Rho kinase in TXA(2)-induced pulmonary vasoconstriction during postnatal maturation.


METHODS
Changes in contractility and intracellular calcium were analyzed in 1 day (newborn) and 2-week-old piglets' pulmonary arteries (PA). K(V) currents were investigated in freshly isolated smooth muscle cells using the whole-cell configuration of the patch clamp technique.


RESULTS
The contractile responses to the TXA(2) mimetic U46619 were similar at both ages but the L-type Ca(2+) channel blocker nifedipine and a PKCzeta pseudosubstrate inhibitor only attenuated the contraction in newborn PA. K(V) currents were similarly inhibited by U46619, although their density was dramatically reduced in 2-week-old as compared to newborn PA smooth muscle cells. This was consistent with a greater contraction to the K(V) inhibitor, 4-aminopyridine, and with a leftward shift in the increase in intracellular Ca(2+) by U46619 in newborn versus older animals. On the other hand, the Rho kinase inhibitor Y-27632 induced a stronger inhibitory effect on the contraction induced by U46619 in 2-week-old than in newborn PA and this was accompanied with minor effects on intracellular calcium levels.


CONCLUSIONS
TXA(2)-induced pulmonary vasoconstriction involves PKCzeta-K(V)-L-type Ca(2+) channel and RhoA/Rho kinase signaling pathways, which are downregulated and upregulated, respectively, during postnatal maturation. The different contribution of these pathways could be of relevant importance for the vasodilator therapy choice in the treatment of pulmonary hypertension.
Cogolludo
Angel
A
Department of Pharmacology, School of Medicine, Universidad Complutense, 28040 Madrid, Spain. acogolludo@ift.csic.es
Moreno
Laura
L
Lodi
Federica
F
Tamargo
Juan
J
Perez-Vizcaino
Francisco
F
D019796:15-Hydroxy-11 alpha,9 alpha-(epoxymethano)prosta-5,13-dienoic Acid / Q000494:pharmacology; D015761:4-Aminopyridine / Q000494:pharmacology; D000375:Aging / Q000502:physiology; D000577:Amides / Q000494:pharmacology; D000818:Animals; D000831:Animals, Newborn; D002118:Calcium / Q000378:metabolism; D002121:Calcium Channel Blockers / Q000494:pharmacology; D020746:Calcium Channels, L-Type / Q000187:drug effects; D004730:Endothelium, Vascular / Q000378:metabolism*; D066298:In Vitro Techniques; D007527:Isoenzymes / Q000037:antagonists & inhibitors / Q000378:metabolism*; D009119:Muscle Contraction / Q000187:drug effects; D009131:Muscle, Smooth, Vascular / Q000187:drug effects / Q000378:metabolism; D009543:Nifedipine / Q000494:pharmacology; D018408:Patch-Clamp Techniques; D024642:Potassium Channels, Voltage-Gated / Q000037:antagonists & inhibitors / Q000378:metabolism*; D011493:Protein Kinase C / Q000037:antagonists & inhibitors / Q000378:metabolism*; D011651:Pulmonary Artery; D011725:Pyridines / Q000494:pharmacology; D015398:Signal Transduction / Q000187:drug effects / Q000502:physiology; D013552:Swine; D013928:Thromboxane A2 / Q000819:agonists; D020742:rhoA GTP-Binding Protein / Q000378:metabolism*
D000577:Amides; D002121:Calcium Channel Blockers; D020746:Calcium Channels, L-Type; D007527:Isoenzymes; D024642:Potassium Channels, Voltage-Gated; D011725:Pyridines; C108830:Y 27632; D013928:Thromboxane A2; D019796:15-Hydroxy-11 alpha,9 alpha-(epoxymethano)prosta-5,13-dienoic Acid; D015761:4-Aminopyridine; D011493:Protein Kinase C; D020742:rhoA GTP-Binding Protein; D009543:Nifedipine; D002118:Calcium