At the cross-point of connexins, calcium, and ATP: blocking hemichannels inhibits vasoconstriction of rat small mesenteric arteries
Autor: | Bert Vanheel, Geert Bultynck, Elke Decrock, Benjamin Wacquier, Geneviève Dupont, Kelly Decaluwé, Johan Van de Voorde, Mélissa Bol, Luc Leybaert, Nan Wang, Marijke De Bock, Ashish A. Gadicherla, Harold V.M. van Rijen, Dmitri V. Krysko |
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Rok vydání: | 2016 |
Předmět: |
0301 basic medicine
P2Y receptor Time Factors Purinergic Antagonists Physiology Vasodilator Agents Cell Communication Connexins Muscle Smooth Vascular Norepinephrine Adenosine Triphosphate Inositol 1 4 5-Trisphosphate Receptors Vasoconstrictor Agents Mesenteric arteries Mice Knockout Microscopy Confocal Models Cardiovascular Gap Junctions Pannexin Purinergic signalling Mesenteric Arteries Phenotype medicine.anatomical_structure cardiovascular system Female medicine.symptom Cardiology and Cardiovascular Medicine Blood vessel medicine.medical_specialty Genotype Myocytes Smooth Muscle In Vitro Techniques Biology Contractility 03 medical and health sciences Physiology (medical) Internal medicine medicine Animals Computer Simulation Calcium Signaling Rats Wistar 030104 developmental biology Endocrinology Vasoconstriction Connexin 43 Biophysics Calcium Peptides Myograph |
Zdroj: | Cardiovascular Research. 113:195-206 |
ISSN: | 1755-3245 0008-6363 |
Popis: | Aims Connexins form gap-junctions (GJs) that directly connect cells, thereby coordinating vascular cell function and controlling vessel diameter and blood flow. GJs are composed of two hemichannels contributed by each of the connecting cells. Hemichannels also exist as non-junctional channels that, when open, lead to the entry/loss of ions and the escape of ATP. Here we investigated cross-talk between hemichannels and Ca2+/purinergic signaling in controlling blood vessel contraction. We hypothesized that hemichannel Ca2+ entry and ATP release contributes to smooth muscle cell (SMC) Ca2+ dynamics, thereby influencing vessel contractility. We applied several peptide modulators of hemichannel function and inhibitors of Ca2+ and ATP signaling to investigate their influence on SMC Ca2+ dynamics and vessel contractility. Methods and Results Confocal Ca2+ imaging studies on small mesenteric arteries (SMAs) from rat demonstrated that norepinephrine-induced SMC Ca2+ oscillations were inhibited by blocking IP3 receptors with xestospongin-C and by interfering with hemichannel function, most notably by the specific Cx43 hemichannel blocking peptide TAT-L2 and by TAT-CT9 that promotes Cx43 hemichannel opening. Evidence for hemichannel involvement in SMC function was supported by the fact that TAT-CT9 significantly increased SMC resting cytoplasmic Ca2+ concentration, indicating it facilitated Ca2+ entry, and by the observation that norepinephrine-triggered vessel ATP release was blocked by TAT-L2. Myograph tension measurements on isolated SMAs showed significant inhibition of norepinephrine-triggered contractility by the ATP receptor antagonist suramin, but the strongest effect was observed with TAT-L2 that gave ~80% inhibition at 37°C. TAT-L2 inhibition of vessel contraction was significantly reduced in conditional Cx43 KO animals, indicating the effect was Cx43 hemichannel-dependent. Computational modeling suggested these results could be explained by the opening of a single hemichannel per SMC. Conclusions These results indicate that Cx43 hemichannels contribute to SMC Ca2+ dynamics and contractility, by facilitating Ca2+ entry, ATP release and purinergic signaling. |
Databáze: | OpenAIRE |
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