1
|
Hansen FB, Esteves GV, Mogensen S, Prat-Duran J, Secher N, Løfgren B, Granfeldt A, Simonsen U. Increased cerebral endothelium-dependent vasodilation in rats in the postcardiac arrest period. J Appl Physiol (1985) 2021; 131:1311-1327. [PMID: 34435510 DOI: 10.1152/japplphysiol.00373.2021] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Cardiovascular lability is common after cardiac arrest. We investigated whether altered endothelial function is present in cerebral and mesenteric arteries 2 and 4 h after resuscitation. Male Sprague-Dawley rats were anesthetized, intubated, ventilated, and intravascularly catheterized whereupon rats were randomized into four groups. Following 7 min of asphyxial cardiac arrest and subsequent resuscitation, cardiac arrest and sham rats were observed for either 2 or 4 h. Neuron-specific enolase levels were measured in blood samples. Middle cerebral artery segments and small mesenteric arteries were isolated and examined in microvascular myographs. qPCR and immunofluorescence analysis were performed on cerebral arteries. In cerebral arteries, bradykinin-induced vasodilation was inhibited in the presence of either calcium-activated K+ channel blockers (UCL1684 and senicapoc) or the nitric oxide (NO) synthase inhibitor, Nω-nitro-L-arginine methyl ester hydrochloride (l-NAME), whereas the combination abolished bradykinin-induced vasodilation across groups. Neuron-specific enolase levels were significantly increased in cardiac arrest rats. Cerebral vasodilation was comparable between the 2-h groups, but markedly enhanced in response to bradykinin, NS309 (an opener of small and intermediate calcium-activated K+ channels), and sodium nitroprusside 4 h after cardiac arrest. Endothelial NO synthase and guanylyl cyclase subunit α-1 mRNA expression was unaltered after 2 h, but significantly decreased 4 h after resuscitation. In mesenteric arteries, the endothelium-dependent vasodilation was comparable between corresponding groups at both 2 and 4 h. Our findings show enhanced cerebral endothelium-dependent vasodilation 4 h after cardiac arrest mediated by potentiated endothelial-derived hyperpolarization and NO pathways. Altered cerebral endothelium-dependent vasodilation may contribute to disturbed cerebral perfusion after cardiac arrest.NEW & NOTEWORTHY This is the first study, to our knowledge, to demonstrate enhanced endothelium-dependent vasodilation in middle cerebral arteries in a cardiac arrest rat model. The increased endothelium-dependent vasodilation was a result of potentiated endothelium-derived hyperpolarization and endothelial nitric oxide pathways. Immunofluorescence microscopy confirmed the presence of relevant receptors and eNOS in cerebral arteries, whereas qPCR showed altered expression of genes related to guanylyl cyclase and eNOS. Altered endothelium-dependent vasoregulation may contribute to disturbed cerebral blood flow in the postcardiac arrest period.
Collapse
Affiliation(s)
- Frederik Boe Hansen
- Department of Biomedicine, Aarhus University, Aarhus, Denmark.,Department of Clinical Medicine, Aarhus University, Aarhus, Denmark
| | | | - Susie Mogensen
- Department of Biomedicine, Aarhus University, Aarhus, Denmark
| | | | - Niels Secher
- Department of Anesthesiology and Intensive Care, Aarhus University Hospital, Aarhus, Denmark
| | - Bo Løfgren
- Research Center for Emergency Medicine, Aarhus University Hospital, Aarhus, Denmark
| | - Asger Granfeldt
- Department of Clinical Medicine, Aarhus University, Aarhus, Denmark.,Department of Anesthesiology and Intensive Care, Aarhus University Hospital, Aarhus, Denmark
| | - Ulf Simonsen
- Department of Biomedicine, Aarhus University, Aarhus, Denmark
| |
Collapse
|
2
|
Hald BO, Welsh DG. Conceptualizing Conduction as a Pliant Vasomotor response: Impact of Ca 2+ fluxes and Ca 2+ Sensitization. Am J Physiol Heart Circ Physiol 2020; 319:H1290-H1301. [PMID: 32946262 DOI: 10.1152/ajpheart.00286.2020] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
Coordinating blood flow to active tissue requires vasomotor responses to conduct among resistance arteries. Vasomotor spread is governed by the electrical and mechanical properties of vessels; the latter being linked to the sigmoid relations between membrane potential (VM), [Ca2+], and smooth muscle contractility. Proteins guiding electrical-to-tone translation are subject to regulation; thus, vasomotor conduction could be viewed as "pliant" to the current regulatory state. Using simple in silico approaches, we explored vasomotor pliancy and how the regulation of contractility impacts conduction along a skeletal muscle artery and a branching cerebrovascular network. Initial simulations revealed how limited electromechanical linearity affects the translation of electrical spread into arterial tone. Subtle changes to the VM-[Ca2+] or [Ca2+]-diameter relationship, akin to regulatory alterations in Ca2+ influx and Ca2+ sensitivity, modified the distance and amplitude of the conducted vasomotor response. Simultaneous changes to both relationships, consistent with agonist stimulation, augmented conduction although the effect varied with stimulus strength and polarity (depolarization vs hyperpolarization). Final simulations using our cerebrovascular network revealed how localized changes to the VM-[Ca2+] or [Ca2+]-diameter relationships could regionally shape conduction without interfering with the electrical spread. We conclude that regulatory changes to key effector proteins (e.g. L-type Ca2+ channels, myosin light chain phosphatase), integral to voltage translation, not only impact conducted vasomotor tone but likely blood flow delivery to active tissues.
Collapse
Affiliation(s)
- Bjørn Olav Hald
- Department of Neuroscience, University of Copenhagen, Denmark
| | - Donald G Welsh
- Robarts Research Institute and the Department of Physiology & Pharmacology, University of Western Ontario, Canada
| |
Collapse
|