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Saha PS, Knecht TM, Arrick DM, Watt MJ, Scholl JL, Mayhan WG. Prenatal exposure to alcohol impairs responses of cerebral arterioles to activation of potassium channels: Role of oxidative stress. Alcohol Clin Exp Res (Hoboken) 2023; 47:87-94. [PMID: 36446735 PMCID: PMC9974881 DOI: 10.1111/acer.14980] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/10/2022] [Revised: 10/24/2022] [Accepted: 11/17/2022] [Indexed: 11/23/2022]
Abstract
BACKGROUND Potassium channels play an important role in the basal tone and dilation of cerebral resistance arterioles in response to many stimuli. However, the effect of prenatal alcohol exposure (PAE) on specific potassium channel function remains unknown. The first goal of this study was to determine the influence of PAE on the reactivity of cerebral arterioles to activation of ATP-sensitive potassium (KATP ) and BK channels. Our second goal was to determine whether oxidative stress contributed to potassium channel dysfunction of cerebral arterioles following PAE. METHODS We fed Sprague-Dawley dams a liquid diet with or without alcohol (3% EtOH) for the duration of their pregnancy (21 to 23 days). We examined in vivo responses of cerebral arterioles in control and PAE male and female offspring (14 to 16 weeks after birth) to activators of potassium channels (Iloprost [BK channels] and pinacidil [KATP channels]), before and following inhibition of oxidative stress with apocynin. RESULTS We found that PAE impaired dilation of cerebral arterioles in response to activation of potassium channels with iloprost and pinacidil, and this impairment was similar in male and female rats. In addition, treatment with apocynin reversed the impaired vasodilation to iloprost and pinacidil in PAE rats to levels observed in control rats. This effect of apocynin also was similar in male and female rats. CONCLUSIONS PAE induces dysfunction in the ability of specific potassium channels to dilate cerebral arterioles which appears to be mediated by an increase in oxidative stress. We suggest that these alterations in potassium channel function may contribute to the pathogenesis of cerebral vascular abnormalities and/or behavioral/cognitive deficits observed in fetal alcohol spectrum disorders.
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Affiliation(s)
- Partha S. Saha
- Division of Basic Biomedical Sciences, Sanford School of Medicine, University of South Dakota, Vermillion, SD 57069
| | - Tiffany M. Knecht
- Division of Basic Biomedical Sciences, Sanford School of Medicine, University of South Dakota, Vermillion, SD 57069
| | - Denise M. Arrick
- Division of Basic Biomedical Sciences, Sanford School of Medicine, University of South Dakota, Vermillion, SD 57069
| | - Michael J. Watt
- Department of Anatomy, University of Otago, Dunedin, New Zealand
| | - Jamie L. Scholl
- Division of Basic Biomedical Sciences, Sanford School of Medicine, University of South Dakota, Vermillion, SD 57069
| | - William G. Mayhan
- Division of Basic Biomedical Sciences, Sanford School of Medicine, University of South Dakota, Vermillion, SD 57069
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Patel S, Fedinec AL, Liu J, Weiss MA, Pourcyrous M, Harsono M, Parfenova H, Leffler CW. H 2S mediates the vasodilator effect of endothelin-1 in the cerebral circulation. Am J Physiol Heart Circ Physiol 2018; 315:H1759-H1764. [PMID: 30265150 DOI: 10.1152/ajpheart.00451.2018] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
Abstract
H2S is an endogenous gasotransmitter that increases cerebral blood flow. In the cerebral vascular endothelium, H2S is produced by cystathionine δ-lyase (CSE). Endothelin-1 (ET-1) has constrictor and dilator influences on the cerebral circulation. The mechanism of the vasodilation caused by ET-1 may involve endothelium-derived factors. We hypothesize that ET-1-elicited dilation of pial arterioles requires an elevation of H2S production in the cerebral vascular endothelium. We investigated the effects of ET-1 on CSE-catalyzed brain H2S production and pial arteriolar diameter using cranial windows in newborn pigs in vivo. H2S was measured in periarachnoid cerebrospinal fluid. ET-1 (10-12-10-8 M) caused an elevation of H2S that was reduced by the CSE inhibitors propargylglycine (PPG) and β-cyano-l-alanine (BCA). Low doses of ET-1 (10-12-10-11 M) produced vasodilation of pial arterioles that was blocked PPG and BCA, suggesting the importance of H2S influences. The vasodilator effects of H2S may require activation of smooth muscle cell membrane ATP-sensitive K+ (KATP) channels and large-conductance Ca2+-activated K+ (BK) channels. The KATP inhibitor glibenclamide and the BK inhibitor paxilline blocked CSE/H2S-dependent dilation of pial arterioles to ET-1. In contrast, the vasoconstrictor response of pial arterioles to 10-8 M ET-1 was not modulated by PPG, BCA, glibenclamide, or paxilline and, therefore, was independent of CSE/H2S influences. Pial arteriolar constriction response to higher levels of ET-1 was independent of CSE/H2S and KATP/BKCa channel activation. These data suggest that H2S is an endothelium-derived factor that mediates the vasodilator effects of ET-1 in the cerebral circulation via a mechanism that involves activation of KATP and BK channels in vascular smooth muscle. NEW & NOTEWORTHY Disorders of the cerebral circulation in newborn infants may lead to lifelong neurological disabilities. We report that vasoactive peptide endothelin-1 exhibits vasodilator properties in the neonatal cerebral circulation by stimulating production of H2S, an endothelium-derived messenger with vasodilator properties. The ability of endothelin-1 to stimulate brain production of H2S may counteract the reduction in cerebral blood flow and prevent the cerebral vascular dysfunction caused by stroke, asphyxia, cerebral hypoxia, ischemia, and vasospasm.
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Affiliation(s)
- Shalinkumar Patel
- Division of Neonatology, Department of Pediatrics, University of Tennessee Health Science Center , Memphis, Tennessee
| | - Alexander L Fedinec
- Laboratory for Research in Neonatal Physiology, Departments of Physiology and Pediatrics, University of Tennessee Health Science Center , Memphis, Tennessee
| | - Jiangxiong Liu
- Laboratory for Research in Neonatal Physiology, Departments of Physiology and Pediatrics, University of Tennessee Health Science Center , Memphis, Tennessee
| | - Max A Weiss
- Laboratory for Research in Neonatal Physiology, Departments of Physiology and Pediatrics, University of Tennessee Health Science Center , Memphis, Tennessee
| | - Massroor Pourcyrous
- Division of Neonatology, Department of Pediatrics, University of Tennessee Health Science Center , Memphis, Tennessee.,Laboratory for Research in Neonatal Physiology, Departments of Physiology and Pediatrics, University of Tennessee Health Science Center , Memphis, Tennessee
| | - Mimily Harsono
- Division of Neonatology, Department of Pediatrics, University of Tennessee Health Science Center , Memphis, Tennessee
| | - Helena Parfenova
- Laboratory for Research in Neonatal Physiology, Departments of Physiology and Pediatrics, University of Tennessee Health Science Center , Memphis, Tennessee
| | - Charles W Leffler
- Division of Neonatology, Department of Pediatrics, University of Tennessee Health Science Center , Memphis, Tennessee.,Laboratory for Research in Neonatal Physiology, Departments of Physiology and Pediatrics, University of Tennessee Health Science Center , Memphis, Tennessee
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Abstract
The stimulation of some facial regions is known to trigger the trigemino-cardiac reflex: the main stimulus is represented by the contact of the face with water. This phenomenon called diving reflex induces a set of reactions in the cardiovascular and respiratory systems occurring in all mammals, especially marine (whales, seals). During the immersion of the face in the water, the main responses are aimed at reducing the oxygen consumption of the organism. Accordingly reduction in heart rate, peripheral vasoconstriction, blood pooling in certain organs, especially the heart, and brain and an increase in blood pressure have been reported. Moreover, the speed and intensity of the reflex is inversely proportional to the temperature of the water: more cold the water, more reactions as described are strong. In the case of deep diving an additional effect, such as blood deviation, has been reported: the blood is sequestered within the lungs, to compensate for the increase in the external pressure, preventing them from collapsing. The trigeminal-cardiac reflex is not just confined to the diving reflex; recently it has been shown that a brief proprioceptive stimulation (10 min) by jaw extension in rats produces interesting effects both at systemic and cerebral levels, reducing the arterial blood pressure, and vasodilating the pial arterioles. The arteriolar dilation is associated with rhythmic diameter changes characterized by an increase in the endothelial activity. Fascinating the stimulation of trigeminal nerve is able to activate the nitric oxide release by vascular endothelial cells. Therefore, the aim of this review was to highlight the effects due to trigeminal cardiac reflex induced by a simple mandibular extension. Opposite effects, such as hypotension, and modulation of cerebral arteriolar tone, were observed, when these responses were compared to those elicited by the diving reflex.
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Affiliation(s)
- Dominga Lapi
- Department of Clinical Medicine and Surgery, "Federico II" University Medical School Naples, Italy
| | - Rossana Scuri
- Department of Translational Research on New Technologies in Medicine and Surgery, University of Pisa Pisa, Italy
| | - Antonio Colantuoni
- Department of Clinical Medicine and Surgery, "Federico II" University Medical School Naples, Italy
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Arrick DM, Yang S, Li C, Cananzi S, Mayhan WG. Vigorous exercise training improves reactivity of cerebral arterioles and reduces brain injury following transient focal ischemia. Microcirculation 2015; 21:516-23. [PMID: 24617555 DOI: 10.1111/micc.12127] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2014] [Accepted: 03/07/2014] [Indexed: 01/29/2023]
Abstract
OBJECTIVE Our objective was to examine whether vigorous exercise training (VExT) could influence nitric oxide synthase (NOS)-dependent vasodilation and transient focal ischemia-induced brain injury. Rats were divided into sedentary (SED) or VExT groups. MATERIALS AND METHODS Exercise was carried out 5 days/week for a period of 8-10 weeks. First, we measured responses of pial arterioles to an eNOS-dependent (ADP), an nNOS-dependent (NMDA) and a NOS-independent (nitroglycerin) agonist in SED and VExT rats. Second, we measured infarct volume in SED and VExT rats following middle cerebral artery occlusion (MCAO). Third, we measured superoxide levels in brain tissue of SED and VExT rats under basal and stimulated conditions. RESULTS We found that eNOS- and nNOS-dependent, but not NOS-independent vasodilation, was increased in VExT compared to SED rats, and this could be inhibited with L-NMMA in both groups. In addition, we found that VExT reduced infarct volume following MCAO when compared to SED rats. Further, superoxide levels were similar in brain tissue from SED and VExT rats under basal and stimulated conditions. CONCLUSIONS We suggest that VExT potentiates NOS-dependent vascular reactivity and reduces infarct volume following MCAO via a mechanism that appears to be independent of oxidative stress, but presumably related to an increase in the contribution of nitric oxide.
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Affiliation(s)
- Denise M Arrick
- Department of Cellular Biology and Anatomy and the Center for Cardiovascular Diseases and Sciences, LSU Health Sciences Center-Shreveport, Shreveport, Louisiana, USA
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Mayhan WG, Arrick DM, Patel KP, Sun H. Exercise training normalizes impaired NOS-dependent responses of cerebral arterioles in type 1 diabetic rats. Am J Physiol Heart Circ Physiol 2011; 300:H1013-20. [PMID: 21169403 PMCID: PMC3064313 DOI: 10.1152/ajpheart.00873.2010] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/31/2010] [Accepted: 12/06/2010] [Indexed: 01/24/2023]
Abstract
Our goal was to examine whether exercise training (ExT) could normalize impaired nitric oxide synthase (NOS)-dependent dilation of cerebral (pial) arterioles during type 1 diabetes (T1D). We measured the in vivo diameter of pial arterioles in sedentary and exercised nondiabetic and diabetic rats in response to an endothelial NOS (eNOS)-dependent (ADP), an neuronal NOS (nNOS)-dependent [N-methyl-D-aspartate (NMDA)], and a NOS-independent (nitroglycerin) agonist. In addition, we measured superoxide anion levels in brain tissue under basal conditions in sedentary and exercised nondiabetic and diabetic rats. Furthermore, we used Western blot analysis to determine eNOS and nNOS protein levels in cerebral vessels/brain tissue in sedentary and exercised nondiabetic and diabetic rats. We found that ADP and NMDA produced a dilation of pial arterioles that was similar in sedentary and exercised nondiabetic rats. In contrast, ADP and NMDA produced only minimal vasodilation in sedentary diabetic rats. ExT restored impaired ADP- and NMDA-induced vasodilation observed in diabetic rats to that observed in nondiabetics. Nitroglycerin produced a dilation of pial arterioles that was similar in sedentary and exercised nondiabetic and diabetic rats. Superoxide levels in cortex tissue were similar in sedentary and exercised nondiabetic rats, were increased in sedentary diabetic rats, and were normalized by ExT in diabetic rats. Finally, we found that eNOS protein was increased in diabetic rats and further increased by ExT and that nNOS protein was not influenced by T1D but was increased by ExT. We conclude that ExT can alleviate impaired eNOS- and nNOS-dependent responses of pial arterioles during T1D.
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Affiliation(s)
- William G Mayhan
- Department of Cellular and Integrative Physiology, University of Nebraska Medical Center, Omaha, Nebraska 68198-5850, USA.
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Leffler CW, Parfenova H, Basuroy S, Jaggar JH, Umstot ES, Fedinec AL. Hydrogen sulfide and cerebral microvascular tone in newborn pigs. Am J Physiol Heart Circ Physiol 2011; 300:H440-7. [PMID: 21131483 PMCID: PMC3044062 DOI: 10.1152/ajpheart.00722.2010] [Citation(s) in RCA: 67] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/21/2010] [Accepted: 11/22/2010] [Indexed: 11/22/2022]
Abstract
Hydrogen sulfide (H2S) is a gaseous signaling molecule that appears to be involved in numerous biological processes, including regulation of blood pressure and vascular tone. The present study is designed to address the hypothesis that H2S is a functionally significant, endogenous dilator in the newborn cerebrovascular circulation. In vivo experiments were conducted using newborn pigs with surgically implanted, closed, cranial windows. Topical application of H2S concentration-dependently (10(-6) to 2×10(-4) M) dilated pial arterioles. This dilation was blocked by glibenclamide (10(-6) M). L-cysteine, the substrate of the H2S-producing enzymes cystathionine γ-lyase (CSE) and cystathionine β-synthase (CBS), also dilated pial arterioles. The dilation to L-cysteine was blocked by the CSE inhibitor d,l-propargylglycine (PPG, 10 mM) but was unaffected by the CBS inhibitor amino-oxyacetate (AOA, 1 mM). Western blots detected CSE, but not CBS, in cerebral microvessels, whereas CBS is detected in brain parenchyma. Immunohistological CSE expression is predominantly vascular while CBS is expressed mainly in neurons and astrocytes. L-cysteine (5 mM) increased H2S concentration in cerebrospinal fluid (CSF), measured by GC-MS, from 561±205 to 2,783±818 nM before but not during treatment with PPG (1,030±70 to 622±78 nM). Dilation to hypercapnia was inhibited by PPG but not AOA. Hypercapnia increased CSF H2S concentration from 763±243 to 4,337±1789 nM before but not during PPG treatment (357±178 vs. 425±217 nM). These data show that H2S is a dilator of the newborn cerebral circulation and that endogenous CSE can produce sufficient H2S to decrease vascular tone. H2S appears to be a physiologically significant dilator in the cerebral circulation.
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Affiliation(s)
- Charles W Leffler
- Laboratory for Research in Neonatal Physiology, Department of Physiology, University of Tennessee Health Science Center, 894 Union Ave., Memphis, TN 38163, USA.
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Abstract
The gaseous compound carbon monoxide (CO) has been identified as an important endogenous biological messenger in brain and is a major component in regulation of cerebrovascular circulation in newborns. CO is produced endogenously by catabolism of heme to CO, free iron, and biliverdin during enzymatic degradation of heme by heme oxygenase (HO). The present study was designed to test the hypothesis that endogenously produced CO contributes to hypotension-induced vasodilation of cerebral arterioles. Experiments used anesthetized piglets with implanted, closed cranial windows. Topical application of the HO substrate heme-l-lysinate caused dilation of pial arterioles that was blocked by a metal porphyrin inhibitor of HO, chromium mesoporphyrin (CrMP). In normotensive piglets (arterial pressure 64 +/- 4 mmHg), CrMP did not cause vasoconstriction of pial arterioles but rather a transient dilation. Hypotension (50% of basal blood pressure) increased cerebral CO production and dilated pial arterioles from 66 +/- 2 to 92 +/- 7 microm. In hypotensive piglets, topical CrMP or intravenous tin protoporphyrin decreased cerebral CO production and produced pial arteriolar constriction to normotensive diameters. In additional experiments, because prostacyclin and nitric oxide (NO) are also key dilators that can contribute to cerebrovascular dilation, we held their levels constant. NO/prostacyclin clamp was accomplished with continuous, simultaneous application of indomethacin, N(omega)-nitro-l-arginine, and minimal dilatory concentrations of iloprost and sodium nitroprusside. With constant NO and prostacyclin, the transient dilator and prolonged constrictor responses to CrMP of normotensive and hypotensive piglets, respectively, were the same as when NO and prostaglandins were not held constant. These data suggest that endogenously produced CO contributes to cerebrovascular dilation in response to reduced perfusion pressure.
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Affiliation(s)
- Alie Kanu
- Dept. of Physiology, Univ. of Tennessee Health Science Center, 894 Union Ave, Memphis, TN 38163, USA
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