1
|
Sackheim AM, Villalba N, Sancho M, Harraz OF, Bonev AD, D’Alessandro A, Nemkov T, Nelson MT, Freeman K. Traumatic Brain Injury Impairs Systemic Vascular Function Through Disruption of Inward-Rectifier Potassium Channels. FUNCTION (OXFORD, ENGLAND) 2021; 2:zqab018. [PMID: 34568829 PMCID: PMC8462507 DOI: 10.1093/function/zqab018] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
Trauma can lead to widespread vascular dysfunction, but the underlying mechanisms remain largely unknown. Inward-rectifier potassium channels (Kir2.1) play a critical role in the dynamic regulation of regional perfusion and blood flow. Kir2.1 channel activity requires phosphatidylinositol 4,5-bisphosphate (PIP2), a membrane phospholipid that is degraded by phospholipase A2 (PLA2) in conditions of oxidative stress or inflammation. We hypothesized that PLA2-induced depletion of PIP2 after trauma impairs Kir2.1 channel function. A fluid percussion injury model of traumatic brain injury (TBI) in rats was used to study mesenteric resistance arteries 24 hours after injury. The functional responses of intact arteries were assessed using pressure myography. We analyzed circulating PLA2, hydrogen peroxide (H2O2), and metabolites to identify alterations in signaling pathways associated with PIP2 in TBI. Electrophysiology analysis of freshly-isolated endothelial and smooth muscle cells revealed a significant reduction of Ba2+-sensitive Kir2.1 currents after TBI. Additionally, dilations to elevated extracellular potassium and BaCl2- or ML 133-induced constrictions in pressurized arteries were significantly decreased following TBI, consistent with an impairment of Kir2.1 channel function. The addition of a PIP2 analog to the patch pipette successfully rescued endothelial Kir2.1 currents after TBI. Both H2O2 and PLA2 activity were increased after injury. Metabolomics analysis demonstrated altered lipid metabolism signaling pathways, including increased arachidonic acid, and fatty acid mobilization after TBI. Our findings support a model in which increased H2O2-induced PLA2 activity after trauma hydrolyzes endothelial PIP2, resulting in impaired Kir2.1 channel function.
Collapse
Affiliation(s)
- Adrian M Sackheim
- Department of Surgery, University of Vermont Larner College of Medicine, Burlington, VT, USA
| | - Nuria Villalba
- Department of Surgery, University of Vermont Larner College of Medicine, Burlington, VT, USA
| | - Maria Sancho
- Department of Pharmacology, University of Vermont Larner College of Medicine, Burlington, VT, USA
| | - Osama F Harraz
- Department of Pharmacology, University of Vermont Larner College of Medicine, Burlington, VT, USA
| | - Adrian D Bonev
- Department of Pharmacology, University of Vermont Larner College of Medicine, Burlington, VT, USA
| | - Angelo D’Alessandro
- Department of Surgery, University of Colorado School of Medicine, Aurora, CO, USA
- Department of Biochemistry and Molecular Genetics, University of Colorado School of Medicine, Aurora, CO, USA
| | - Travis Nemkov
- Department of Biochemistry and Molecular Genetics, University of Colorado School of Medicine, Aurora, CO, USA
| | - Mark T Nelson
- Department of Pharmacology, University of Vermont Larner College of Medicine, Burlington, VT, USA
- Division of Cardiovascular Sciences, University of Manchester, Manchester, UK
| | - Kalev Freeman
- Department of Surgery, University of Vermont Larner College of Medicine, Burlington, VT, USA
- Department of Pharmacology, University of Vermont Larner College of Medicine, Burlington, VT, USA
- Address correspondence to K.F. (e-mail: )
| |
Collapse
|
2
|
Peart JN, Gross GJ. Cardioprotective effects of acute and chronic opioid treatment are mediated via different signaling pathways. Am J Physiol Heart Circ Physiol 2006; 291:H1746-53. [PMID: 16731654 DOI: 10.1152/ajpheart.00233.2006] [Citation(s) in RCA: 59] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
A 5-day exposure to morphine exerts a profound cardioprotective phenotype in murine hearts. In the present study, we examined mechanisms by which morphine generates this effect, exploring the roles of Gi and Gs proteins, PKA, PKC, and β-adrenergic receptors (β-AR) in acute and chronic opioid preconditioning. Langendorff-perfused hearts from placebo, acute morphine (AM; 10 μmol/l)-, or chronic morphine (CM)-treated mice (75-mg pellet, 5 days) underwent 25-min ischemia and 45-min reperfusion. After reperfusion, placebo-treated hearts exhibited marked contractile and diastolic dysfunction [rate-pressure product (RPP), 40 ± 4% baseline; end-diastolic pressure (EDP), 33 ± 3 mmHg], whereas AM hearts showed significant improvement in recovery of RPP and EDP (60 ± 3% and 23 ± 4 mmHg, respectively; P < 0.05 vs. placebo). Furthermore, CM hearts demonstrated a complete return of diastolic function and significantly greater recovery of contractile function (83 ± 3%, P < 0.05 vs. both placebo and AM). Pretreatment with Gi protein inhibitor pertussis toxin abolished AM protection while partially attenuating CM recovery ( P < 0.05 vs. placebo). Treatment with Gs inhibitor NF-449 did not affect AM preconditioning yet completely abrogated CM preconditioning. Similarly, PKA inhibition significantly attenuated the ischemia-tolerant state afforded by CM, whereas it was ineffective in AM hearts. PKC inhibition with chelerythrine was ineffective in CM hearts while completely abrogating AM preconditioning. Moreover, whereas β1-AR blockade with CGP-20712A failed to alter recovery in CM hearts, the β2-AR antagonist ICI-118,551 significantly attenuated postischemic recovery. These data describe novel findings whereby CM preconditioning is mediated by a PKC-independent pathway involving PKA, β2-AR, and Gs proteins, whereas AM preconditioning is mediated via Gi proteins and PKC.
Collapse
Affiliation(s)
- Jason N Peart
- Heart Foundation Research Center, Griffith Univ., PMB 50 Gold Coast Mail Center, Brisbane, Qld., 9726, Australia.
| | | |
Collapse
|