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Colburn TD, Weber RE, Schulze KM, Sue Hageman K, Horn AG, Behnke BJ, Poole DC, Musch TI. Sexual dimorphism in vascular ATP-sensitive K + channel function supporting interstitial PO2 via convective and/or diffusive O 2 transport. J Physiol 2021; 599:3279-3293. [PMID: 34101850 PMCID: PMC8451062 DOI: 10.1113/jp281120] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2020] [Accepted: 04/14/2021] [Indexed: 11/08/2022] Open
Abstract
KEY POINTS Inhibition of pancreatic ATP-sensitive K+ (KATP ) channels is the intended effect of oral sulphonylureas to increase insulin release in diabetes. However, pertinent to off-target effects of sulphonylurea medication, sex differences in cardiac KATP channel function exist, whereas potential sex differences in vascular KATP channel function remain unknown. In the present study, we assessed vascular KATP channel function (topical glibenclamide superfused onto fast-twitch oxidative skeletal muscle) supporting blood flow and interstitial O2 delivery-utilization matching ( P O 2 is) during twitch contractions in male, female during pro-oestrus and ovariectomized female (F+OVX) rats. Glibenclamide decreased blood flow (convective O2 transport) and interstitial P O 2 in male and female, but not F+OVX, rats. Compared to males, females also demonstrated impaired diffusive O2 transport and a faster fall in interstitial P O 2 . Our demonstration, in rats, that sex differences in vascular KATP channel function exist support the tentative hypothesis that oral sulphonylureas may exacerbate exercise intolerance and morbidity, especially in premenopausal females. ABSTRACT Vascular ATP-sensitive K+ (KATP ) channels support skeletal muscle blood flow ( Q ̇ m ), interstitial O2 delivery ( Q ̇ O 2 )-utilization ( V ̇ O 2 ) matching (i.e. interstitial-myocyte O2 flux driving pressure; P O 2 is) and exercise tolerance. Potential sex differences in skeletal muscle vascular KATP channel function remain largely unexplored. We hypothesized that local skeletal muscle KATP channel inhibition via glibenclamide superfusion (5 mg kg-1 GLI; sulphonylurea diabetes medication) in anaesthetized female Sprague-Dawley rats, compared to males, would demonstrate greater reductions in contracting (1 Hz, 7 V, 180 s) fast-twitch oxidative mixed gastrocnemius (97% type IIA+IID/X+IIB) Q ̇ m (15 μm microspheres) and P O 2 is (phosphorescence quenching), resulting from more compromised convective ( Q ̇ O 2 ) and diffusive ( D O 2 ) O2 conductances. Furthermore, these GLI-induced reductions in ovary-intact females measured during pro-oestrus would be diminished following ovariectomy (F+OVX). GLI similarly impaired mixed gastrocnemius V ̇ O 2 in both males (↓28%) and females (↓33%, both P < 0.032) via reduced Q ̇ m (male: ↓31%, female: ↓35%, both P < 0.020), Q ̇ O 2 (male: 5.6 ± 0.5 vs. 4.0 ± 0.5, female: 6.4 ± 1.1 vs. 4.2 ± 0.6 mL O2 min-1 100 g tissue-1 , P < 0.022) and the resulting P O 2 is, with females also demonstrating a reduced D O 2 (0.40 ± 0.07 vs. 0.30 ± 0.04 mL O2 min-1 100 g tissue-1 , P < 0.042) and a greater GLI-induced speeding of P O 2 is fall (mean response time: Sex × Drug interaction, P = 0.026). Conversely, GLI did not impair the mixed gastrocnemius of F+OVX rats. Therefore, in patients taking sulphonylureas, these results support the potential for impaired vascular KATP channel function to compromise muscle Q ̇ m and therefore exercise tolerance. Such an effect, if present, would likely contribute to adverse cardiovascular events in premenopausal females more than males.
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Affiliation(s)
- Trenton D. Colburn
- Department of Kinesiology, Physiology, Kansas State University, Manhattan, KS, 66506, USA
| | - Ramona E. Weber
- Department of Kinesiology, Physiology, Kansas State University, Manhattan, KS, 66506, USA
| | - Kiana M. Schulze
- Department of Kinesiology, Physiology, Kansas State University, Manhattan, KS, 66506, USA
| | - K. Sue Hageman
- Department of Anatomy and Physiology, Kansas State University, Manhattan, KS, 66506, USA
| | - Andrew G. Horn
- Department of Kinesiology, Physiology, Kansas State University, Manhattan, KS, 66506, USA
| | - Brad J. Behnke
- Department of Kinesiology, Physiology, Kansas State University, Manhattan, KS, 66506, USA
| | - David C. Poole
- Department of Kinesiology, Physiology, Kansas State University, Manhattan, KS, 66506, USA
- Department of Anatomy and Physiology, Kansas State University, Manhattan, KS, 66506, USA
| | - Timothy I. Musch
- Department of Kinesiology, Physiology, Kansas State University, Manhattan, KS, 66506, USA
- Department of Anatomy and Physiology, Kansas State University, Manhattan, KS, 66506, USA
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Hirai DM, Tabuchi A, Craig JC, Colburn TD, Musch TI, Poole DC. Regulation of capillary hemodynamics by K ATP channels in resting skeletal muscle. Physiol Rep 2021; 9:e14803. [PMID: 33932103 PMCID: PMC8087980 DOI: 10.14814/phy2.14803] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2021] [Accepted: 02/22/2021] [Indexed: 12/25/2022] Open
Abstract
ATP-sensitive K+ channels (KATP ) have been implicated in the regulation of resting vascular smooth muscle membrane potential and tone. However, whether KATP channels modulate skeletal muscle microvascular hemodynamics at the capillary level (the primary site for blood-myocyte O2 exchange) remains unknown. We tested the hypothesis that KATP channel inhibition would reduce the proportion of capillaries supporting continuous red blood cell (RBC) flow and impair RBC hemodynamics and distribution in perfused capillaries within resting skeletal muscle. RBC flux (fRBC ), velocity (VRBC ), and capillary tube hematocrit (Hctcap ) were assessed via intravital microscopy of the rat spinotrapezius muscle (n = 6) under control (CON) and glibenclamide (GLI; KATP channel antagonist; 10 µM) superfusion conditions. There were no differences in mean arterial pressure (CON:120 ± 5, GLI:124 ± 5 mmHg; p > 0.05) or heart rate (CON:322 ± 32, GLI:337 ± 33 beats/min; p > 0.05) between conditions. The %RBC-flowing capillaries were not altered between conditions (CON:87 ± 2, GLI:85 ± 1%; p > 0.05). In RBC-perfused capillaries, GLI reduced fRBC (CON:20.1 ± 1.8, GLI:14.6 ± 1.3 cells/s; p < 0.05) and VRBC (CON:240 ± 17, GLI:182 ± 17 µm/s; p < 0.05) but not Hctcap (CON:0.26 ± 0.01, GLI:0.26 ± 0.01; p > 0.05). The absence of GLI effects on the %RBC-flowing capillaries and Hctcap indicates preserved muscle O2 diffusing capacity (DO2 m). In contrast, GLI lowered both fRBC and VRBC thus impairing perfusive microvascular O2 transport (Q̇m) and lengthening RBC capillary transit times, respectively. Given the interdependence between diffusive and perfusive O2 conductances (i.e., %O2 extraction∝DO2 m/Q̇m), such GLI alterations are expected to elevate muscle %O2 extraction to sustain a given metabolic rate. These results support that KATP channels regulate capillary hemodynamics and, therefore, microvascular gas exchange in resting skeletal muscle.
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Affiliation(s)
- Daniel M. Hirai
- Department of Health and KinesiologyPurdue UniversityWest LafayetteIndianaUSA,Department of KinesiologyKansas State UniversityManhattanKansasUSA
| | - Ayaka Tabuchi
- Department of KinesiologyKansas State UniversityManhattanKansasUSA,Department of Engineering ScienceUniversity of Electro‐CommunicationsTokyoJapan
| | - Jesse C. Craig
- Department of KinesiologyKansas State UniversityManhattanKansasUSA,Department of Internal MedicineUniversity of UtahSalt Lake CityUtahUSA,Geriatric ResearchEducation and Clinical CenterVeterans Affairs Medical CenterSalt Lake CityUtahUSA
| | | | - Timothy I. Musch
- Department of KinesiologyKansas State UniversityManhattanKansasUSA,Department of Anatomy and PhysiologyKansas State UniversityManhattanKansasUSA
| | - David C. Poole
- Department of KinesiologyKansas State UniversityManhattanKansasUSA,Department of Anatomy and PhysiologyKansas State UniversityManhattanKansasUSA
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Colburn TD, Weber RE, Hageman KS, Caldwell JT, Schulze KM, Ade CJ, Behnke BJ, Poole DC, Musch TI. Vascular ATP-sensitive K + channels support maximal aerobic capacity and critical speed via convective and diffusive O 2 transport. J Physiol 2020; 598:4843-4858. [PMID: 32798233 PMCID: PMC7874302 DOI: 10.1113/jp280232] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2020] [Accepted: 08/13/2020] [Indexed: 12/26/2022] Open
Abstract
KEY POINTS Oral sulphonylureas, widely prescribed for diabetes, inhibit pancreatic ATP-sensitive K+ (KATP ) channels to increase insulin release. However, KATP channels are also located within vascular (endothelium and smooth muscle) and muscle (cardiac and skeletal) tissue. We evaluated left ventricular function at rest, maximal aerobic capacity ( V ̇ O2 max) and submaximal exercise tolerance (i.e. speed-duration relationship) during treadmill running in rats, before and after systemic KATP channel inhibition via glibenclamide. Glibenclamide impaired critical speed proportionally more than V ̇ O2 max but did not alter resting cardiac output. Vascular KATP channel function (topical glibenclamide superfused onto hindlimb skeletal muscle) resolved a decreased blood flow and interstitial PO2 during twitch contractions reflecting impaired O2 delivery-to-utilization matching. Our findings demonstrate that systemic KATP channel inhibition reduces V ̇ O2 max and critical speed during treadmill running in rats due, in part, to impaired convective and diffusive O2 delivery, and thus V ̇ O2 , especially within fast-twitch oxidative skeletal muscle. ABSTRACT Vascular ATP-sensitive K+ (KATP ) channels support skeletal muscle blood flow and microvascular oxygen delivery-to-utilization matching during exercise. However, oral sulphonylurea treatment for diabetes inhibits pancreatic KATP channels to enhance insulin release. Herein we tested the hypotheses that: i) systemic KATP channel inhibition via glibenclamide (GLI; 10 mg kg-1 i.p.) would decrease cardiac output at rest (echocardiography), maximal aerobic capacity ( V ̇ O2 max) and the speed-duration relationship (i.e. lower critical speed (CS)) during treadmill running; and ii) local KATP channel inhibition (5 mg kg-1 GLI superfusion) would decrease blood flow (15 µm microspheres), interstitial space oxygen pressures (PO2 is; phosphorescence quenching) and convective and diffusive O2 transport ( Q ̇ O2 and DO2 , respectively; Fick Principle and Law of Diffusion) in contracting fast-twitch oxidative mixed gastrocnemius muscle (MG: 9% type I+IIa fibres). At rest, GLI slowed left ventricular relaxation (2.11 ± 0.59 vs. 1.70 ± 0.23 cm s-1 ) and decreased heart rate (321 ± 23 vs. 304 ± 22 bpm, both P < 0.05) while cardiac output remained unaltered (219 ± 64 vs. 197 ± 39 ml min-1 , P > 0.05). During exercise, GLI reduced V ̇ O2 max (71.5 ± 3.1 vs. 67.9 ± 4.8 ml kg-1 min-1 ) and CS (35.9 ± 2.4 vs. 31.9 ± 3.1 m min-1 , both P < 0.05). Local KATP channel inhibition decreased MG blood flow (52 ± 25 vs. 34 ± 13 ml min-1 100 g tissue-1 ) and PO2 isnadir (5.9 ± 0.9 vs. 4.7 ± 1.1 mmHg) during twitch contractions. Furthermore, MG V ̇ O2 was reduced via impaired Q ̇ O2 and DO2 (P < 0.05 for each). Collectively, these data support that vascular KATP channels help sustain submaximal exercise tolerance in healthy rats. For patients taking sulfonylureas, KATP channel inhibition may exacerbate exercise intolerance.
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Affiliation(s)
- Trenton D Colburn
- Department of Kinesiology, Kansas State University, Manhattan, KS, 66506, USA
| | - Ramona E Weber
- Department of Kinesiology, Kansas State University, Manhattan, KS, 66506, USA
| | - K Sue Hageman
- Department of Anatomy and Physiology, Kansas State University, Manhattan, KS, 66506, USA
| | - Jacob T Caldwell
- Department of Kinesiology, Kansas State University, Manhattan, KS, 66506, USA
| | - Kiana M Schulze
- Department of Kinesiology, Kansas State University, Manhattan, KS, 66506, USA
| | - Carl J Ade
- Department of Kinesiology, Kansas State University, Manhattan, KS, 66506, USA
| | - Brad J Behnke
- Department of Kinesiology, Kansas State University, Manhattan, KS, 66506, USA
| | - David C Poole
- Department of Kinesiology, Kansas State University, Manhattan, KS, 66506, USA
- Department of Anatomy and Physiology, Kansas State University, Manhattan, KS, 66506, USA
| | - Timothy I Musch
- Department of Kinesiology, Kansas State University, Manhattan, KS, 66506, USA
- Department of Anatomy and Physiology, Kansas State University, Manhattan, KS, 66506, USA
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Colburn TD, Holdsworth CT, Craig JC, Hirai DM, Montgomery S, Poole DC, Musch TI, Kenney MJ. ATP-sensitive K + channel inhibition in rats decreases kidney and skeletal muscle blood flow without increasing sympathetic nerve discharge. Respir Physiol Neurobiol 2020; 278:103444. [PMID: 32330600 DOI: 10.1016/j.resp.2020.103444] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2020] [Revised: 04/11/2020] [Accepted: 04/13/2020] [Indexed: 01/06/2023]
Abstract
ATP-sensitive K+ (KATP) channels contribute to exercise-induced hyperemia in skeletal muscle either locally by vascular hyperpolarization or by sympathoinhibition and decreased sympathetic vasoconstriction. However, mean arterial pressure (MAP) regulation via baroreceptors and subsequent efferent activity may confound assessment of vascular versus neural KATP channel function. We hypothesized that systemic KATP channel inhibition via glibenclamide (GLI) would increase MAP without increasing sympathetic nerve discharge (SND). Lumbar and renal nerve SND were measured in anesthetized male rats with intact baroreceptors (n = 12) and sinoaortic denervated (SAD; n = 4) counterparts and blood flow (BF) and vascular conductance (VC) assessed in conscious rats (n = 6). GLI increased MAP (p < 0.05) and transiently decreased HR in intact (p < 0.05), but not SAD rats. Renal (-30 %) and lumbar (-40 %) ΔSND decreased in intact but increased in SAD rats (∼40 % and 20 %; p < 0.05). BF and VC decreased in kidneys and total hindlimb skeletal muscle (p < 0.05). Thus, because KATP inhibition decreases SND, GLI-induced reductions in blood flow cannot result from enhanced sympathetic activity.
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Affiliation(s)
- Trenton D Colburn
- Department of Kinesiology, Kansas State University, Manhattan, KS 66506, USA.
| | - Clark T Holdsworth
- Department of Anatomy and Physiology, Kansas State University, Manhattan, KS 66506, USA
| | - Jesse C Craig
- Department of Kinesiology, Kansas State University, Manhattan, KS 66506, USA
| | - Daniel M Hirai
- Department of Kinesiology, Kansas State University, Manhattan, KS 66506, USA
| | - Shawnee Montgomery
- Department of Anatomy and Physiology, Kansas State University, Manhattan, KS 66506, USA
| | - David C Poole
- Department of Kinesiology, Kansas State University, Manhattan, KS 66506, USA; Department of Anatomy and Physiology, Kansas State University, Manhattan, KS 66506, USA
| | - Timothy I Musch
- Department of Kinesiology, Kansas State University, Manhattan, KS 66506, USA; Department of Anatomy and Physiology, Kansas State University, Manhattan, KS 66506, USA
| | - Michael J Kenney
- College of Science, University of Texas at El Paso, El Paso, TX 79902, USA
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Sakaguchi R, Mori Y. Transient receptor potential (TRP) channels: Biosensors for redox environmental stimuli and cellular status. Free Radic Biol Med 2020; 146:36-44. [PMID: 31682917 DOI: 10.1016/j.freeradbiomed.2019.10.415] [Citation(s) in RCA: 50] [Impact Index Per Article: 12.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/26/2019] [Revised: 10/26/2019] [Accepted: 10/29/2019] [Indexed: 12/26/2022]
Abstract
Transient receptor potential (TRP) channels are a family of cation channels that depolarizes the membrane potential and regulates intracellular concentrations of cations such as Ca2+. TRP channels are also known to function as "biosensors" to detect changes of the surrounding environment and cellular status. Lines of evidence have unveiled that numerous proteins are subject to redox modification and subsequent signaling. For example, TRPM2, TRPC5, TRPV1, and TRPA1 are known as redox sensors activated by hydrogen peroxide (H2O2), nitric oxide (NO), and electrophiles. Thus, these channels facilitate the influx of cations which in turn triggers the appropriate cellular responses against environmental redox stimuli and cellular redox status. In this review, we focus on the recent findings regarding the functions of TRP channels in relation to other ion channels, and other proteins which also go through redox modification of cysteine (Cys) residues. We aim to understand the structural and molecular basis of the redox-sensing mechanisms of TRP channels in exerting various functions under physiological conditions as well as pathological conditions such as cancer malignancy. Their future potential as drug targets will also be discussed.
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Affiliation(s)
- Reiko Sakaguchi
- Laboratory of Molecular Biology, Department of Synthetic Chemistry and Biological Chemistry, Graduate School of Engineering, Kyoto University, Kyoto, 615-8510, Japan; The World Premier International Research Initiative-Institute for Integrated Cell-Material Sciences, Kyoto University, Kyoto, 615-8510, Japan
| | - Yasuo Mori
- Laboratory of Molecular Biology, Department of Synthetic Chemistry and Biological Chemistry, Graduate School of Engineering, Kyoto University, Kyoto, 615-8510, Japan; The World Premier International Research Initiative-Institute for Integrated Cell-Material Sciences, Kyoto University, Kyoto, 615-8510, Japan.
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Vascular K ATP channels mitigate severe muscle O 2 delivery-utilization mismatch during contractions in chronic heart failure rats. Respir Physiol Neurobiol 2017; 238:33-40. [PMID: 28119150 DOI: 10.1016/j.resp.2017.01.009] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2016] [Revised: 01/10/2017] [Accepted: 01/18/2017] [Indexed: 12/14/2022]
Abstract
The vascular ATP-sensitive K+ (KATP) channel is a mediator of skeletal muscle microvascular oxygenation (PO2mv) during contractions in health. We tested the hypothesis that KATP channel function is preserved in chronic heart failure (CHF) and therefore its inhibition would reduce PO2mv and exacerbate the time taken to reach the PO2mv steady-state during contractions of the spinotrapezius muscle. Moreover, we hypothesized that subsequent KATP channel activation would oppose the effects of this inhibition. Muscle PO2mv (phosphorescence quenching) was measured during 180s of 1-Hz twitch contractions (∼6V) under control, glibenclamide (GLI, KATP channel antagonist; 5mg/kg) and pinacidil (PIN, KATP channel agonist; 5mg/kg) conditions in 16 male Sprague-Dawley rats with CHF induced via myocardial infarction (coronary artery ligation, left ventricular end-diastolic pressure: 18±1mmHg). GLI reduced baseline PO2mv (control: 28.3±0.9, GLI: 24.8±1.0mmHg, p<0.05), lowered mean PO2mv (average PO2mv during the overall time taken to reach the steady-state; control: 20.6±0.6, GLI: 17.6±0.3mmHg, p<0.05), and slowed the attainment of steady-state PO2mv (overall mean response time; control: 66.1±10.2, GLI: 93.6±7.8s, p<0.05). PIN opposed these effects on the baseline PO2mv, mean PO2mv and time to reach the steady-state PO2mv (p<0.05 for all vs. GLI). Inhibition of KATP channels exacerbates the transient mismatch between muscle O2 delivery and utilization in CHF rats and this effect is opposed by PIN. These data reveal that the KATP channel constitutes one of the select few well-preserved mechanisms of skeletal muscle microvascular oxygenation control in CHF.
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