Kv1.3 channels facilitate the connection between metabolism and blood flow in the heart.
*contrast echocardiography; *coronary blood flow; *Coronary Circulation/drug effects; *coronary microcirculation; *Kv 1.3 channels; Animals; Kv1.3 Potassium Channel/*physiology; Mice; Myocardium/*metabolism; Potassium Channel Blockers/pharmacology; Regional Blood Flow/drug effects; Triterpenes/pharmacology; Vasodilation/drug effects
The connection between metabolism and flow in the heart, metabolic dilation, is essential for cardiac function. We recently found redox-sensitive Kv1.5 channels play a role in coronary metabolic dilation; however, more than one ion channel likely plays a role in this process as animals null for these channels still showed limited coronary metabolic dilation. Accordingly, we examined the role of another Kv1 family channel, the energetically linked Kv1.3 channel, in coronary metabolic dilation. We measured myocardial blood flow (contrast echocardiography) during norepinephrine-induced increases in cardiac work (heart rate x mean arterial pressure) in WT, WT mice given correolide (preferential Kv1.3 antagonist), and Kv1.3-null mice (Kv1.3(-/-) ). We also measured relaxation of isolated small arteries mounted in a myograph. During increased cardiac work, myocardial blood flow was attenuated in Kv1.3(-/-) and in correolide-treated mice. In isolated vessels from Kv1.3(-/-) mice, relaxation to H2 O2 was impaired (vs WT), but responses to adenosine and acetylcholine were equivalent to WT. Correolide reduced dilation to adenosine and acetylcholine in WT and Kv1.3(-/-) , but had no effect on H2 O2 -dependent dilation in vessels from Kv1.3(-/-) mice. We conclude that Kv1.3 channels participate in the connection between myocardial blood flow and cardiac metabolism.
Ohanyan Vahagn; Yin Liya; Bardakjian Raffi; Kolz Christopher; Enrick Molly; Hakobyan Tatevik; Luli Jordan; Graham Kathleen; Khayata Mohamed; Logan Suzanna; Kmetz John; Chilian William M
Microcirculation (New York, N.Y. : 1994)
2017
2017-05
Article information provided for research and reference use only. All rights are retained by the journal listed under publisher and/or the creator(s).
<a href="http://doi.org/10.1111/micc.12334" target="_blank" rel="noreferrer noopener">10.1111/micc.12334</a>
Requisite Role of Kv1.5 Channels in Coronary Metabolic Dilation.
129 Strain; Animals; cardiac function; contrast echocardiography; Coronary Circulation/*physiology; Coronary Vessels/*metabolism; hydrogen peroxide; Inbred C57BL; ion channel; Knockout; Kv1.5 Potassium Channel/*physiology; Mice; Muscle; Smooth; Transgenic; transgenic mice; Vascular/*metabolism; vasodilation; Vasodilation/*physiology; voltage-gated potassium channels
RATIONALE: In the working heart, coronary blood flow is linked to the production of metabolites, which modulate tone of smooth muscle in a redox-dependent manner. Voltage-gated potassium channels (Kv), which play a role in controlling membrane potential in vascular smooth muscle, have certain members that are redox-sensitive. OBJECTIVE: To determine the role of redox-sensitive Kv1.5 channels in coronary metabolic flow regulation. METHODS AND RESULTS: In mice (wild-type [WT], Kv1.5 null [Kv1.5(-/-)], and Kv1.5(-/-) and WT with inducible, smooth muscle-specific expression of Kv1.5 channels), we measured mean arterial pressure, myocardial blood flow, myocardial tissue oxygen tension, and ejection fraction before and after inducing cardiac stress with norepinephrine. Cardiac work was estimated as the product of mean arterial pressure and heart rate. Isolated arteries were studied to establish whether genetic alterations modified vascular reactivity. Despite higher levels of cardiac work in the Kv1.5(-/-) mice (versus WT mice at baseline and all doses of norepinephrine), myocardial blood flow was lower in Kv1.5(-/-) mice than in WT mice. At high levels of cardiac work, tissue oxygen tension dropped significantly along with ejection fraction. Expression of Kv1.5 channels in smooth muscle in the null background rescued this phenotype of impaired metabolic dilation. In isolated vessels from Kv1.5(-/-) mice, relaxation to H2O2 was impaired, but responses to adenosine and acetylcholine were normal compared with those from WT mice. CONCLUSIONS: Kv1.5 channels in vascular smooth muscle play a critical role in coupling myocardial blood flow to cardiac metabolism. Absence of these channels disassociates metabolism from flow, resulting in cardiac pump dysfunction and tissue hypoxia.
Ohanyan Vahagn; Yin Liya; Bardakjian Raffi; Kolz Christopher; Enrick Molly; Hakobyan Tatevik; Kmetz John; Bratz Ian; Luli Jordan; Nagane Masaki; Khan Nadeem; Hou Huagang; Kuppusamy Periannan; Graham Jacqueline; Fu Frances Kwan; Janota Danielle; Oyewumi Moses O; Logan Suzanna; Lindner Jonathan R; Chilian William M
Circulation research
2015
2015-09
Article information provided for research and reference use only. All rights are retained by the journal listed under publisher and/or the creator(s).
<a href="http://doi.org/10.1161/CIRCRESAHA.115.306642" target="_blank" rel="noreferrer noopener">10.1161/CIRCRESAHA.115.306642</a>