1
|
Pinheiro‐da‐Silva J, Luchiari AC. Embryonic ethanol exposure on zebrafish early development. Brain Behav 2021; 11:e02062. [PMID: 33939334 PMCID: PMC8213935 DOI: 10.1002/brb3.2062] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/06/2020] [Revised: 12/01/2020] [Accepted: 01/11/2021] [Indexed: 12/20/2022] Open
Abstract
INTRODUCTION Embryonic exposure to ethanol leads to a condition of physical, behavioral, and cognitive deficiencies named fetal alcohol spectrum disorders (FASD). The most severe variations are in fetal alcohol syndrome (FAS), which is easier to diagnose and not studied in animal models. On the other side, the pFAS (partial fetal alcohol syndrome) includes cases of alcohol-related congenital disabilities and neurodevelopmental disorder with an inconclusive diagnosis. In recent years, the zebrafish has become a valuable model to study FASD and its variations. METHODS This study characterizes the zebrafish embryonic and larval development after low and moderate ethanol concentration exposure. Fish eggs were exposed to 0.0%, 0.25%, 0.5%, and 1.0% ethanol at 24 hr postfertilization, and embryonic development was observed every 8 hr up to 120 hpf. It evaluated movements, phenotypic abnormalities, hatching, cardiac function and heartbeat frequency, larvae length at 120 hpf, and the apoptotic cells' fluorescence stained with acridine orange. RESULTS Embryonic exposure to 0.5% and 1% ethanol presented reduced body size, decreased heartbeat rate, higher numbers of apoptotic cells, and hatching time differences. CONCLUSIONS Our results suggest any ethanol exposure during embryogenesis can be harmful and reinforces zebrafish as a suitable model for fetal alcohol spectrum disorders (FASD).
Collapse
Affiliation(s)
| | - Ana Carolina Luchiari
- Physiology and Behavior DepartmentFederal University of Rio Grande do NorteNatalBrazil
| |
Collapse
|
2
|
Katary M, Abdel-Rahman AA. Alcohol suppresses cardiovascular diurnal variations in male normotensive rats: Role of reduced PER2 expression and CYP2E1 hyperactivity in the heart. Alcohol 2020; 89:27-36. [PMID: 32777474 DOI: 10.1016/j.alcohol.2020.08.001] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2020] [Revised: 06/26/2020] [Accepted: 08/04/2020] [Indexed: 01/01/2023]
Abstract
BACKGROUND AND AIMS The molecular mechanism of the adverse effects of ethanol on diurnal cardiovascular regulation remains unknown. In separate studies, the cardiac circadian rhythm protein period-2 (PER2) confers cardioprotection and, in other organs, PER2 interaction with the ethanol-metabolizing enzyme CYP2E1 underlies, via heme oxygenase-1 (HO-1) upregulation, tissue injury/dysfunction. Here, we hypothesized that suppressed PER2 expression and elevated CYP2E1/HO-1 levels in the heart underlie the disrupted diurnal cardiovascular rhythm/function in alcohol-fed normotensive rats. METHODS In ethanol-fed (5%, w/v; 8 weeks) or isocaloric liquid diet-fed male rats, diurnal changes in blood pressure (BP), heart rate (HR), HR vagal variability index, root mean square of successive beat-to-beat differences in beat-interval duration (rMSSD), and cardiac function were measured by radiotelemetry and echocardiography followed by ex vivo molecular studies. RESULTS Radiotelemetry findings showed ethanol-evoked reductions in BP (during the dark cycle), rMSSD (during both cycles), and in diurnal differences in BP and rMSSD. Echocardiography findings revealed significant (p < 0.05) reductions in ejection fraction and fractional shortening (weeks 4-6) in the absence of cardiac remodeling (collagen content). Hearts of ethanol-fed rats exhibited higher (p < 0.05) CYP2E1 activity (50%) and HO-1 expression (63%), along with reduction (p < 0.05) in PER2 levels (29%), compared with the hearts of isocaloric diet-fed control rats. CONCLUSIONS Our novel findings implicate upregulations of CYP2E1/HO-1 and downregulation of the circadian rhythm cardioprotective protein PER2, in the heart, in the chronic deleterious diurnal cardiovascular effects of alcohol in male rats.
Collapse
Affiliation(s)
- Mohamed Katary
- Department of Pharmacology and Toxicology, Brody School of Medicine, East Carolina University, Greenville, NC, United States
| | - Abdel A Abdel-Rahman
- Department of Pharmacology and Toxicology, Brody School of Medicine, East Carolina University, Greenville, NC, United States.
| |
Collapse
|
3
|
Cifuentes F, Paredes A, Palacios J, Muñoz F, Carvajal L, Nwokocha CR, Morales G. Hypotensive and antihypertensive effects of a hydroalcoholic extract from Senecio nutans Sch. Bip. (Compositae) in mice: Chronotropic and negative inotropic effect, a nifedipine-like action. JOURNAL OF ETHNOPHARMACOLOGY 2016; 179:367-374. [PMID: 26724424 DOI: 10.1016/j.jep.2015.12.048] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/30/2015] [Revised: 12/22/2015] [Accepted: 12/22/2015] [Indexed: 06/05/2023]
Abstract
ETHNOPHARMACOLOGICAL RELEVANCE Senecio nutans Sch. Bip. (Compositae) is an endemic plant of South America used in the management of acute mountain sickness in the Andean communities. Currently, the direct effects of hydroalcoholic extract from S. nutans on the cardiovascular system are unknown. The aim of this study was to determine the effects and mechanism of action of S. nutans on cardiovascular function in normotensive and Angiotensin II (1μg/mL) hypertension mice models. MATERIAL AND METHODS Blood pressure and ECG measurements were simultaneously carried out on the mice and rats. The isolated right atrium, papillary muscle of the left ventricle and isolated heart of rat were used to study the cardiac functions and mechanisms. RESULTS S. nutans (40mg/Kg) induced a 30% and 12% significant (p<0.05) reduction of the mean arterial pressure (MAP) in normotensive and hypertensive mice respectively. This decrease was as a result of decrease in heart rate (HR) in normotensive (25%) and hypertensive model (31%). It also decreased the sinus rhythm in isolated right atrium of rat. Compared with Losartan, a known anti-hypertensive, S. nutans caused a dose-dependent negative inotropic effect (dP/dtmax) on Langendorff isolated heart system. While Losartan, decreased the MAP by 30% but had no effect on heart rate. The calcium blocker nifedipine had similar effects as S. nutans, decreasing the beat frequency of isolated right atrium and contractility of papillary muscle of the left ventricle of rat. CONCLUSION The results suggest an important clinical function in hypertension therapy, as S. nutans could decrease the blood pressure in hypertensive mice by decreasing the HR and contractility, leading to a reduction in myocardial oxygen demand.
Collapse
Affiliation(s)
| | - Adrián Paredes
- Laboratorio de Química Biológica, Instituto Antofagasta (IA), Universidad de Antofagasta, Antofagasta, Chile
| | - Javier Palacios
- Departamento de Ciencias Químicas y Farmacéuticas, Facultad de Ciencias de la Salud, Universidad Arturo Prat, Iquique, Chile.
| | | | | | - Chukwuemeka R Nwokocha
- Department of Basic Medical Sciences Physiology Section, Faculty of Medical Sciences, The University of the West Indies, Mona, Kingston 7, Jamaica, W.I
| | - Glauco Morales
- Laboratorio de Química Biológica, Instituto Antofagasta (IA), Universidad de Antofagasta, Antofagasta, Chile
| |
Collapse
|
4
|
Kato T, Masuda Y, Miyano K, Higashiyama M, Yano H, Haque T, Sato F, Yoshida A. Distinct association between the antagonistic jaw muscle activity levels and cardiac activity during chewing and NREM sleep in the freely moving guinea pigs. Neurosci Lett 2015; 592:59-63. [PMID: 25748316 DOI: 10.1016/j.neulet.2015.03.004] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2015] [Revised: 02/20/2015] [Accepted: 03/02/2015] [Indexed: 10/23/2022]
Abstract
The aim of this study was to investigate the changes of the association between cardiac activity and the electromyographic (EMG) level of the antagonistic jaw muscles during chewing and NREM sleep in guinea pigs after systemic clonidine injections. Ten animals were prepared for chronic experiments to monitor sleep, cardiac activity and EMG activity of jaw-closing masseter (MAS) and jaw-opening anterior belly of digastric (ADG) muscles. The recordings were made for ten hours with the injections of saline or clonidine (10 μg/kg, i.p.). Integrated EMG activity of the two muscles and mean heart rate (mHR) were calculated for every 10-s epoch. During the two hours after clonidine injection, the duration of REM sleep and mHR were significantly reduced. During chewing, the high EMG activity level of the two muscles and the activity ratio between the two muscles were not modified although mHR was decreased. During NREM sleep, after clonidine injection, the low EMG activity level at baseline was further decreased by 20-30% in parallel to a decrease of mHR although the heterogeneity of the activity ratio remained unaltered. The results suggest that the maintenance of the activity level for the antagonistic jaw muscles are regulated by the distinct physiological mechanisms reflecting the behavioral states during conscious chewing and unconscious NREM sleep.
Collapse
Affiliation(s)
- Takafumi Kato
- Osaka University Graduate School of Dentistry, Department of Oral Anatomy and Neurobiology, Japan.
| | - Yuji Masuda
- Matsumoto Dental University, Graduate School of Oral Medicine, Department of Oral and Maxillofacial Biology, Japan
| | - Keiji Miyano
- Osaka University Graduate School of Dentistry, Department of Fixed Prosthodontics, Japan
| | - Makoto Higashiyama
- Osaka University Graduate School of Dentistry, Department of Fixed Prosthodontics, Japan
| | - Hiroyuki Yano
- Osaka University Graduate School of Dentistry, Department of Oral and Maxillofacial Surgery II, Japan
| | - Tahsinul Haque
- Osaka University Graduate School of Dentistry, Department of Oral Anatomy and Neurobiology, Japan
| | - Fumihiko Sato
- Osaka University Graduate School of Dentistry, Department of Oral Anatomy and Neurobiology, Japan
| | - Atsushi Yoshida
- Osaka University Graduate School of Dentistry, Department of Oral Anatomy and Neurobiology, Japan
| |
Collapse
|
5
|
El-Mas MM, Abdel-Rahman AA. Endothelial and neuronal nitric oxide synthases variably modulate the oestrogen-mediated control of blood pressure and cardiovascular autonomic control. Clin Exp Pharmacol Physiol 2014; 41:246-54. [PMID: 24471817 DOI: 10.1111/1440-1681.12207] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2013] [Revised: 12/09/2013] [Accepted: 12/18/2013] [Indexed: 11/27/2022]
Abstract
1. We have shown previously that long-term oestrogen (E2) replacement lowers blood pressure (BP) and improves cardiovascular autonomic control in ovariectomized (OVX) rats. In the present study, we investigated whether constitutive and/or inducible (i) nitric oxide synthase (NOS) modulate these E2 effects. 2. We evaluated changes in BP, myocardial contractility index (dP/dtmax ) and power spectral indices of haemodynamic variability following selective inhibition of endothelial (e) NOS with N(5)-(1-iminoethyl)-L-ornithine (L-NIO), neuronal (n) NOS with N(ω)-propyl-L-arginine (NPLA) or iNOS with 1400W in telemetered OVX rats treated for 16 weeks with (OVXE2) or without (control; OVXC) E2. 3. The OVXE2 rats exhibited: (i) reduced BP and increased dP/dtmax ; (ii) cardiac parasympathetic dominance, as reflected by the reduced low-frequency (LF; 0.25-0.75 Hz)/high-frequency (HF; 0.75-3 Hz) ratio of interbeat intervals (IBI(LF/HF)); and (iii) reduced LF oscillations of systolic BP, suggesting a reduced vasomotor sympathetic tone. Inhibition of eNOS (L-NIO; 20 mg/kg, i.p.) elicited a shorter-lived pressor response in OVXE2 than OVXC, rats along with reductions in dP/dtmax and increases in the spectral index of spontaneous baroreflex sensitivity (index α). Treatment with 1 mg/kg, i.p., NPLA reduced BP and increased the IBI(LF/HF) ratio in OVXE2 but not OVXC rats. The iNOS inhibitor 1400W (5 mg/kg, i.p.) caused no haemodynamic changes in OVXC or OVXE2 rats. 4. Overall, constitutive NOS isoforms exert restraining tonic modulatory BP effects that encompass eNOS-mediated reductions and nNOS-mediated elevations in BP in OVXE2 rats. Baroreflex facilitation and dP/dtmax reductions may account for the shorter pressor action of L-NIO in E2-treated, compared with untreated, OVX rats.
Collapse
Affiliation(s)
- Mahmoud M El-Mas
- Department of Pharmacology and Toxicology, School of Medicine, East Carolina University, Greenville, NC, USA
| | | |
Collapse
|
6
|
El-Mas MM, Abdel-Rahman AA. Cardiovascular autonomic modulation by nitric oxide synthases accounts for the augmented enalapril-evoked hypotension in ethanol-fed female rats. Alcohol 2013; 47:339-46. [PMID: 23683529 DOI: 10.1016/j.alcohol.2013.03.004] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2012] [Revised: 01/30/2013] [Accepted: 03/25/2013] [Indexed: 02/01/2023]
Abstract
In this study, we investigated the role of nitric oxide synthase (NOS) isoforms in the enhanced enalapril-evoked hypotension in ethanol-fed female rats by examining the effect of the selective inhibitors of eNOS [N(5)-(1-iminoethyl)-l-ornithine; l-NIO], nNOS (N(ω)-propyl-l-arginine; NPLA), or iNOS (1400W) inhibition on the cardiovascular effects of enalapril in ethanol- (5% w/v) fed rats and in their pair-fed controls. In liquid diet-fed control rats, enalapril- (10 mg/kg) evoked hypotension was abolished by l-NIO (20 mg/kg), but not by NPLA (1 mg/kg) or 1400W (5 mg/kg), suggesting a preferential role for eNOS in this response. Enalapril had no effect on spectral indices of hemodynamic variability or +dP/dtmax (myocardial contractility). However, in ethanol-fed rats, the greater enalapril-evoked hypotension was associated with reductions in (i) +dP/dtmax, (ii) low-frequency/high-frequency ratio of interbeat intervals (IBILF/HF), suggesting cardiac parasympathetic dominance, and (iii) low-frequency spectral band of systolic blood pressure (BP), a marker of vasomotor sympathetic tone. While NPLA or 1400W attenuated the enalapril-evoked hemodynamic and autonomic responses in ethanol-fed rats, l-NIO virtually abolished the hypotensive response and was more efficacious in rectifying autonomic responses to enalapril. Together, these findings implicate NOS isoforms, particularly eNOS, in the altered cardiovascular autonomic control that leads to the augmented enalapril-evoked hypotension in ethanol-fed female rats.
Collapse
Affiliation(s)
- Mahmoud M El-Mas
- Department of Pharmacology and Toxicology, Brody School of Medicine, East Carolina University, Greenville, NC 27834, USA
| | | |
Collapse
|
7
|
El-Mas MM, Fan M, Abdel-Rahman AA. Differential modulation by vascular nitric oxide synthases of the ethanol-evoked hypotension and autonomic dysfunction in female rats. Alcohol 2012; 46:727-35. [PMID: 23046587 DOI: 10.1016/j.alcohol.2012.09.001] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2012] [Revised: 08/24/2012] [Accepted: 09/06/2012] [Indexed: 01/11/2023]
Abstract
We recently reported that chronic exposure to ethanol lowers blood pressure (BP) via altering cardiac contractility and autonomic control in female rats. In this investigation we conducted pharmacological and molecular studies to elucidate the role of constitutive and inducible nitric oxide synthase (NOS) in these hemodynamic effects of ethanol. Changes caused by selective inhibition of eNOS [N(5)-(1-iminoethyl)-l-ornithine; l-NIO], nNOS (N(ω)-propyl-l-arginine; NPLA), or iNOS (1400W) in BP, heart rate (HR), myocardial contractility index (dP/dt(max)), and power spectral indices of hemodynamic variability were evaluated in telemetered female rats receiving ethanol (5%, w/v) or control liquid diet for 8 weeks. Ethanol increased plasma nitrite/nitrate (NOx) and enhanced the phosphorylation of eNOS and nNOS, but not iNOS, in the tail artery. Ethanol also reduced BP, +dP/dt(max), low-frequency bands of interbeat intervals (IBI(LF), 0.25-0.75 Hz) and IBI(LF/HF) ratio while high-frequency bands (IBI(HF), 0.75-3 Hz) were increased, suggesting parasympathetic overactivity. l-NIO (20 mg/kg i.p.) caused greater increases in BP in control than in ethanol-fed rats but elicited similar reductions in IBI(LF/HF) and +dP/dt(max) both groups. NPLA (1 mg/kg i.p.) caused minimal effects in control rats but exacerbated the reductions in BP, +dP/dt(max), and IBI(LF/HF) in ethanol-fed rats. No hemodynamic modifications were caused by 1400W (5 mg/kg i.p.) in either rat group. Together, these findings suggest that nNOS acts tonically to offset the detrimental cardiovascular actions of ethanol in female rats, and the enhanced vascular NO bioavailability may explain the blunted l-NIO evoked pressor response in ethanol-fed rats.
Collapse
Affiliation(s)
- Mahmoud M El-Mas
- Department of Pharmacology and Toxicology, School of Medicine, East Carolina University, Greenville, NC 27834, USA
| | | | | |
Collapse
|
8
|
El-Mas MM, Abdel-Rahman AA. Chronic ethanol attenuates centrally-mediated hypotension elicited via alpha(2)-adrenergic, but not I(1)-imidazoline, receptor activation in female rats. Life Sci 2008; 84:111-8. [PMID: 19041658 DOI: 10.1016/j.lfs.2008.11.006] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2008] [Revised: 10/03/2008] [Accepted: 11/07/2008] [Indexed: 11/26/2022]
Abstract
AIMS This study dealt with the effect of chronic ethanol administration on hemodynamic responses elicited by alpha(2)-adrenergic (alpha-methyldopa) or I(1)-imidazoline (rilmenidine) receptor activation in telemetered female rats. MAIN METHODS The effects of alpha-methyldopa or rilmenidine on blood pressure (BP), heart rate (HR) and their variability were investigated in rats that received liquid diet without or with ethanol (5% w/v) for 12 weeks. To evaluate the effect of each drug on cardiovascular autonomic control (BP and HR variability) in the absence or presence of ethanol, three time-domain indices of hemodynamic variability were measured: (i) standard deviation of mean arterial pressure (SDMAP), (ii) standard deviation of beat-to-beat intervals, and (iii) root mean square of successive differences in R-R intervals. KEY FINDINGS In liquid diet-fed control rats, i.p. rilmenidine (600 microg/kg) or alpha-methyldopa (100 mg/kg) reduced BP along with decreases and increases, respectively, in HR. Both drugs had no effect on HR variability but reduced BP variability (SDMAP), suggesting a reduced vasomotor sympathetic tone. Ethanol feeding attenuated reductions in BP and SDMAP evoked by alpha-methyldopa but not by rilmenidine. SIGNIFICANCE We conclude that chronic ethanol preferentially compromises alpha(2)- but not I(1)-receptor-mediated hypotension in female rats probably via modulation of vasomotor sympathetic activity. These findings highlight the adequacy of rilmenidine use to lower BP in hypertensive alcoholic females.
Collapse
Affiliation(s)
- Mahmoud M El-Mas
- Department of Pharmacology, School of Medicine, East Carolina University, Greenville, NC 27834, USA
| | | |
Collapse
|
9
|
El-Mas MM, Abdel-Rahman AA. Role of Myocardial Contractility and Autonomic Control in the Hypotensive Response to a Limited Access Ethanol Paradigm in SHRs. Alcohol Clin Exp Res 2007; 31:1071-9. [PMID: 17428291 DOI: 10.1111/j.1530-0277.2007.00395.x] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
BACKGROUND Previous experimental studies that evaluated the chronic hemodynamic effect of ethanol employed the continuous exposure protocol of ethanol, which does not mimic the pattern of alcohol consumption in humans. This study dealt with the long-term hemodynamic and cardiovascular autonomic effects of ethanol, in a limited-access regimen in telemetered spontaneously hypertensive rats (SHRs). METHODS Changes in blood pressure (BP), heart rate (HR), myocardial contractility (dP/dt(max)), and spectral cardiovascular autonomic profiles during the ethanol exposure period (2.5 or 5% w/v, 8 h/d, 8:30 am till 4:30 pm) were followed for 12 weeks. RESULTS Compared with control pair-fed SHRs, body weight and urine output, osmolality, and potassium levels were decreased in SHRs receiving 5% but not 2.5% ethanol. Blood pressure showed progressive falls during ethanol-feeding periods with a maximum effect observed at week 5. The peak hypotensive effect was maintained thereafter in SHRs receiving 5% ethanol in contrast to steady rises in BP in the 2.5% ethanol group to near-control levels by the conclusion of the study. Heart rate was slightly but significantly increased by ethanol 5% whereas dP/dt(max) showed persistent reductions. Power spectral analysis showed that ethanol attenuated the baroreflex gain of HR as suggested by the reductions in index alpha, the spectral index of spontaneous baroreflex sensitivity (BRS). CONCLUSIONS It is concluded that limited access ethanol drinking in SHRs elicited hypotension that was concentration dependent and mediated, at least partly, through reductions in myocardial contractility. Baroreflex sensitivity attenuation by ethanol appeared to have limited the tachycardic response to ethanol and perhaps its capacity to offset the evoked hypotension.
Collapse
Affiliation(s)
- Mahmoud M El-Mas
- Department of Pharmacology, School of Medicine, East Carolina University, Greenville, North Carolina 27834, USA
| | | |
Collapse
|
10
|
El-Mas MM, Abdel-Rahman AA. Intermittent Clonidine Regimen Abolishes Tolerance to Its Antihypertensive Effect: A Spectral Study. J Cardiovasc Pharmacol 2007; 49:174-81. [PMID: 17414230 DOI: 10.1097/fjc.0b013e3180318afb] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
The development of tolerance to the antihypertensive effect of clonidine and related imidazolines is clinically recognized. Here, we employed a restricted daytime (8:30 AM until 4:30 PM) clonidine regimen to establish a model of sustained hypotension in spontaneously hypertensive rats (SHRs). Blood pressure (BP), heart rate (HR), and myocardial contractility (dP/dt(max)) were measured by radiotelemetry in pair-fed SHRs receiving liquid diets with or without clonidine (150 microg/kg per day) for 12 weeks. The cardiovascular autonomic control was assessed by power spectral analysis [fast Fourier transformations (FFT)] of hemodynamic variability. Clonidine had no effect on dP/dt(max) and significantly decreased BP and HR during the 8 hour exposure periods throughout the study duration. BP returned to control levels during overnight periods, with no signs of rebound hypertension. FFT analysis of interbeat intervals (IBI) showed pronounced decreases and increases of spectral powers in low-frequency (IBI-LF, 0.20-0.75 Hz) and high-frequency (IBI-HF, 0.75-3 Hz) bands, respectively, in clonidine-treated rats. The IBI(LF/HF) ratio was significantly reduced by clonidine, suggesting cardiac parasympathetic dominance. Clonidine also decreased the vasomotor sympathetic tone, as reflected by the reduced BP-LF spectral density. The sympathoinhibitory effect of clonidine is further confirmed by the significant reductions in urinary norepinephrine levels. Clonidine increased urine output during the 8 hour treatment period but not during the 24 hour period. Plasma and urine osmolality and electrolytes were not altered by clonidine. It is concluded that by adopting the limited-access paradigm, tolerance to the hypotensive and sympathoinhibitory actions of clonidine and, possibly, its side effects, could be minimized.
Collapse
Affiliation(s)
- Mahmoud M El-Mas
- Department of Pharmacology, School of Medicine, East Carolina University, Greenville, NC, USA
| | | |
Collapse
|
11
|
Hallare A, Nagel K, Köhler HR, Triebskorn R. Comparative embryotoxicity and proteotoxicity of three carrier solvents to zebrafish (Danio rerio) embryos. ECOTOXICOLOGY AND ENVIRONMENTAL SAFETY 2006; 63:378-88. [PMID: 16125774 DOI: 10.1016/j.ecoenv.2005.07.006] [Citation(s) in RCA: 72] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/28/2005] [Revised: 07/06/2005] [Accepted: 07/08/2005] [Indexed: 05/04/2023]
Abstract
The present study examines the effects of ethanol (ETOH), dimethyl sulfoxide (DMSO), and acetone on zebrafish embryos and the implications of the observed results on the use of these solvents to zebrafish early life stage tests. The embryos were exposed to different concentrations (0.0, 0.0001, 0.001, 0.01, 0.1, 0.05, 1, 1.5, and 2.0% v/v) of the respective solvents by diluting reagent-grade solvent with reconstituted water [DIN 38415-6-Suborganismische Testverfahren (Gruppe T) Teil 6: Giftigkeit gegenüber Fischen. Deutsches Institute für Normung e.V]. The following endpoints were investigated (mortality, hatching rate, abnormalities, heart rate, and hsp 70 induction). No effect on survival was recorded for both acetone and DMSO even up to the highest concentration. On the other hand, embryos exposed to 1.5% and 2.0% ethanol showed a significant reduction in survival rate. No developmental defects occurred with any of the solvents at the 0.1% concentration. However, starting with 1.0%, weak to very pronounced abnormalities (weak pigmentation, edema, crooked bodies, eye defect, tail defect, reduced heartbeat, and abnormal hatching) were observed depending on the solvent type and the concentration used. Ethanol has been shown to be the most embryotoxic solvent while DMSO and acetone have comparably lesser effects. Heat shock protein 70 was induced by all solvents but at different concentration ranges. DMSO has been shown to be the most potent inducer of stress proteins. Based on the study, the chemicals tested here may be used as carrier solvents in the zebrafish embryo assay at levels below 1.5, 1.5, and 1% v/v for acetone, DMSO, and ethanol, respectively. For stress protein analysis of the exposed embryos, however, the solvent levels should be below 0.1%, 0.01%, and 1.5%, respectively. Additional and separate investigations utilizing other biomarkers should be carried out to further validate the suitability of using these solvents in a typical zebrafish embryo assay.
Collapse
Affiliation(s)
- Arnold Hallare
- Animal Physiological Ecology, University of Tübingen, 72072 Tübingen, Germany.
| | | | | | | |
Collapse
|
12
|
El-Mas MM, Abdel-Rahman AA. Autonomic Modulation of Altered Diurnal Hemodynamic Profiles in Ethanol-Fed Hypertensive Rats. Alcohol Clin Exp Res 2005; 29:499-508. [PMID: 15834214 DOI: 10.1097/01.alc.0000159108.23375.b6] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
Abstract
BACKGROUND A recent report from the authors' laboratory showed that circadian hemodynamic rhythms are altered in hypertension due partly to irregularities in cardiovascular autonomic control. This study investigated the long-term effects of chronic ethanol feeding (5% w/v, 12 weeks) on the circadian profiles of blood pressure (BP), heart rate (HR), and their variability in spontaneously hypertensive rats (SHRs) and age-matched Wistar-Kyoto (WKY) rats. METHODS Radiotelemetry was used for hemodynamic monitoring. The time-domain measures of the variability of BP (standard deviation of mean arterial pressure [SDMAP]) and HR (standard deviation of R-R intervals [SDRR] and root mean square of successive differences in R-R intervals [rMSSD]) were taken as indices of cardiovascular autonomic activity. RESULTS Control WKY rats displayed normal circadian rhythms (i.e., higher dark-time compared with light-time values) of BP, HR, and their variability indices during weeks 6 through 12 of the study. These circadian rhythms were abolished (BP), inverted (HR, SDMAP), or enhanced (SDRR, rMSSD) in SHRs. Ethanol feeding produced sustained hypotension during both light and dark cycles that was 3-fold greater in SHRs than in WKY rats. SDMAP was not affected by ethanol in WKY rats and showed reductions, mostly during light times, in SHRs. Ethanol also caused significant increases in HR in SHRs only during dark periods, probably because of the inhibition of cardiac vagal activity as indicated by temporal reductions in rMSSD. CONCLUSIONS These results implicate autonomic factors in the altered diurnal hemodynamic profile by ethanol in SHRs and highlight the possibility of increased risk of cardiac events in hypertensive patients due to alcohol use.
Collapse
Affiliation(s)
- Mahmoud M El-Mas
- Department of Pharmacology, School of Medicine, East Carolina University, Greenville, North Carolina 27858, USA
| | | |
Collapse
|
13
|
El-Mas MM, Abdel-Rahman AA. Longitudinal studies on the effect of hypertension on circadian hemodynamic and autonomic rhythms in telemetered rats. Life Sci 2005; 76:901-15. [PMID: 15589967 DOI: 10.1016/j.lfs.2004.10.002] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2004] [Accepted: 09/23/2004] [Indexed: 11/23/2022]
Abstract
This study dealt with the long-term effects of hypertension on circadian rhythms of hemodynamic and cardiovascular autonomic functions in radiotelemetered rats. Blood pressure (BP), heart rate (HR), spontaneous locomotor activity, and respiration.were monitored in spontaneously hypertensive rats (SHRs), a model of human hypertension, from 14 to 27 weeks of age and in Wistar-Kyoto rats (WKY) as controls. Cardiovascular autonomic changes were determined by time-domain analysis of the variability of BP (standard deviation of mean arterial pressure, SDMAP) and HR (standard deviation of R-R intervals, SDRR, and the root mean square of successive differences in R-R intervals, rMSSD). Compared with WKY rats, the 24-hr MAP and SDMAP were higher at week 14 in SHRs and showed stepwise increases over the study duration, suggesting progressive increases in vasomotor sympathetic activity in hypertensive rats. Also, higher SDRR, rMSSD, and activity and lower HR and respiration were demonstrated in SHRs. Normal circadian rhythms (higher dark-time values) of MAP, HR, SDMAP, and SDRR were evident in WKY rats at week 20 and continued thereafter. Compared with WKY rats, the circadian BP and HR patterns were abolished and inverted, respectively, in SHRs. Lower dark-time, compared with light-time, SDMAP values were observed in SHRs that were associated with temporal increases in HR variability indices. These findings demonstrate that hypertension elicits significant alterations in circadian autonomic and hemodynamic profiles. Further, the steady increases in BP, average level and oscillations, in SHRs may explain the reported progressive age-related vascular and cardiac hypertrophy in these rats.
Collapse
Affiliation(s)
- Mahmoud M El-Mas
- Department of Pharmacology, School of Medicine, East Carolina University, Greenville, NC 27858, USA
| | | |
Collapse
|
14
|
Omar AG, El-Mas MM. Time-Domain Evaluation of Cyclosporine Interaction with Hemodynamic Variability in Rats. Cardiovasc Drugs Ther 2004; 18:461-8. [PMID: 15770433 DOI: 10.1007/s10557-004-6223-1] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
This study investigated the effects of chronic exposure of Wistar rats to the immunosuppressant drug cyclosporine on blood pressure, heart rate, and their variability and the role of sympathovagal balance in this interaction. The blood pressure variability was determined as the standard deviation of the mean arterial pressure (SDMAP). Two time-domain heart rate variability indices were employed, the standard deviation of beat-to-beat intervals (SDRR) and the root mean square of successive beat-to-beat differences in R-R interval durations (rMSSD). Subcutaneous cyclosporine administration (20 mg/kg/day) for 12 days had no effect on blood pressure or its variability index (SDMAP). In contrast, the average level of heart rate and its variability indices (SDRR and rMSSD) showed significant increases and decreases, respectively, in cyclosporine- compared with vehicle-treated rats. Vagal (atropine) or beta -adrenergic (propranolol) blockade had no effect on blood pressure but elicited increases and decreases, respectively, in heart rate. Compared with control rats, cyclosporine-treated rats exhibited lesser tachycardic responses to atropine and greater bradycardic responses to propranolol, suggesting alterations of cardiac vagal (attenuation) and sympathetic (enhancement) activity by cyclosporine. Further, atropine reduced indices of heart rate variability (rMSSD and SDRR) in control rats, effects that were blunted by cyclosporine treatment. On the other hand, propranolol had no effect on heart rate variability in either cyclosporine-treated or control rats. These findings implicate vagally-mediated alterations in the cardiac sympathovagal balance in the cyclosporine-induced impairment of heart rate oscillations.
Collapse
Affiliation(s)
- Amal G Omar
- Department of Pharmacology, Faculty of Pharmacy, University of Alexandria, Alexandria, Egypt
| | | |
Collapse
|
15
|
El-Mas MM, Abdel-Rahman AA. Contrasting effects of chronic ethanol feeding on centrally and peripherally evoked hypotension in telemetered female rats. Vascul Pharmacol 2004; 41:59-66. [PMID: 15196476 DOI: 10.1016/j.vph.2004.05.001] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2004] [Revised: 04/12/2004] [Accepted: 05/13/2004] [Indexed: 11/19/2022]
Abstract
Our previous studies have shown that ethanol compromises hypotension produced by centrally acting antihypertensive agents in normotensive and hypertensive male rats. The present study investigated whether female rats are as susceptible as male rats to the deleterious effect of ethanol on centrally evoked hypotension. The study was extended to investigate ethanol effects on the time-domain indices of variability in blood pressure [standard deviation of mean arterial pressure (SDMAP)] and heart rate [standard deviation of beat-to-beat intervals (SDRR) and root mean square of successive differences in R-R intervals (rMSSD)]. The hemodynamic effects of a single intraperitoneal dose of clonidine (30 microg/kg) were evaluated in radiotelemetered ethanol-fed (5%, 12 weeks) and pair-fed control Sprague-Dawley rats. In control rats, clonidine caused a significant reduction in MAP that continued for at least 6 h and was associated with reductions in SDMAP and SDRR but not rMSSD, suggesting inhibition of central sympathetic tone. A maximum hypotensive response of -16.4+/-1.7 mm Hg was demonstrated 40 min after clonidine administration. Ethanol feeding significantly attenuated clonidine hypotension whereas it potentiated the associated reduction in SDMAP. To verify the selectivity of ethanol-clonidine interaction, the effects of ethanol on peripherally mediated hemodynamic responses to hydralazine (0.5 mg/kg ip) were investigated. In contrast to its antagonistic effect on clonidine hypotension, ethanol significantly potentiated the hypotensive effect of hydralazine. Together, these findings demonstrate that chronic ethanol feeding exerts opposite effects on centrally (attenuation) and peripherally (potentiation) evoked hypotension in female rats. The interaction of ethanol with antihypertensive agents may not be related to changes in hemodynamic variability.
Collapse
Affiliation(s)
- Mahmoud M El-Mas
- Department of Pharmacology, School of Medicine, East Carolina University, Greenville, NC 27858, USA
| | | |
Collapse
|
16
|
El-Mas MM, Abdel-Rahman AA. Differential modulation by estrogen of alpha2-adrenergic and I1-imidazoline receptor-mediated hypotension in female rats. J Appl Physiol (1985) 2004; 97:1237-44. [PMID: 15145918 DOI: 10.1152/japplphysiol.00401.2004] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
We have recently shown that estrogen negatively modulates the hypotensive effect of clonidine (mixed alpha2-/I1-receptor agonist) in female rats and implicates the cardiovascular autonomic control in this interaction. The present study investigated whether this effect of estrogen involves interaction with alpha2- and/or I1-receptors. Changes evoked by a single intraperitoneal injection of rilmenidine (600 microg/kg) or alpha-methyldopa (100 mg/kg), selective I1- and alpha2-receptor agonists, respectively, in blood pressure, hemodynamic variability, and locomotor activity were assessed in radiotelemetered sham-operated and ovariectomized (Ovx) Sprague-Dawley female rats with or without 12-wk estrogen replacement. Three time domain indexes of hemodynamic variability were employed: the standard deviation of mean arterial pressure as a measure of blood pressure variability and the standard deviation of beat-to-beat intervals (SDRR) and the root mean square of successive differences in R-wave-to-R-wave intervals as measures of heart rate variability. In sham-operated rats, rilmenidine or alpha-methyldopa elicited similar hypotension that lasted at least 5 h and was associated with reductions in standard deviation of mean arterial pressure. SDRR was reduced only by alpha-methyldopa. Ovx significantly enhanced the hypotensive response to alpha-methyldopa, in contrast to no effect on rilmenidine hypotension. The enhanced alpha-methyldopa hypotension in Ovx rats was paralleled with further reduction in SDRR and a reduced locomotor activity. Estrogen replacement (17beta-estradiol subcutaneous pellet, 14.2 microg/day, 12 wk) of Ovx rats restored the hemodynamic and locomotor effects of alpha-methyldopa to sham-operated levels. These findings suggest that estrogen downregulates alpha2- but not I1-receptor-mediated hypotension and highlight a role for the cardiac autonomic control in alpha-methyldopa-estrogen interaction.
Collapse
Affiliation(s)
- Mahmoud M El-Mas
- Dept. of Pharmacology, School of Medicine, East Carolina Univ., Greenville, NC 27858, USA
| | | |
Collapse
|
17
|
El-Mas MM, Abdel-Rahman AA. Effects of Long-Term Ovariectomy and Estrogen Replacement on Clonidine-Evoked Reductions in Blood Pressure and Hemodynamic Variability. J Cardiovasc Pharmacol 2004; 43:607-15. [PMID: 15071346 DOI: 10.1097/00005344-200405000-00001] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
The present study investigated the influence of 12-week ovariectomy (OVX) and estrogen supplementation (OVXE2) on the acute effects of the centrally acting antihypertensive agent clonidine on blood pressure, hemodynamic variability, and locomotor activity in Sprague-Dawley rats. The effects of estrogen depletion and repletion on the peripherally mediated hypotensive response to hydralazine were also evaluated to determine the selectivity of estrogen-clonidine interaction. The radiotelemetry technique was used for blood pressure and locomotor activity measurements. Three time-domain indices of hemodynamic variability were employed: (1). the standard deviation of mean arterial pressure (SDMAP) as a measure of blood pressure variability, and (2). the standard deviation of R-R intervals (SDRR) and the root mean square of successive differences in R-R intervals (rMSSD) as measures of heart rate variability. In control (sham-operated) rats, clonidine (30 microg/kg, i.p.) elicited significant decreases in MAP, blood pressure variability (SDMAP), and overall heart rate variability (SDRR). The reductions in MAP and its variability index (SDMAP) were significantly augmented in OVX rats and restored to sham-operated levels after estrogen replacement (17beta-estradiol subcutaneous pellet, 14.2 microg/d, 12 weeks). The locomotor activity was reduced by clonidine only in OVX rats. In contrast to clonidine, hydralazine (0.5 mg/kg, i.p.) hypotension was not altered by OVX or estrogen replacement. These findings suggest that estrogen negatively modulates centrally evoked hypotension versus no effect on hypotension of peripheral origin. Further, the results implicate the cardiovascular autonomic control in the enhanced hypotensive response to clonidine in OVX rats.
Collapse
Affiliation(s)
- Mahmoud M El-Mas
- Department of Pharmacology, School of Medicine, East Carolina University, Greenville, NC 27858, USA
| | | |
Collapse
|
18
|
El-Mas MM, Abdel-Rahman AA. Chronic ethanol–clonidine hemodynamic interaction in telemetered spontaneously hypertensive rats. Vascul Pharmacol 2004; 41:107-13. [PMID: 15380736 DOI: 10.1016/j.vph.2004.08.001] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2004] [Accepted: 08/19/2004] [Indexed: 11/20/2022]
Abstract
Our previous studies have established that ethanol, administered acutely or chronically, attenuates the hypotensive action of the centrally acting drug clonidine. In this study, we employed the radiotelemetry technique to evaluate the long-term hemodynamic interaction between the two drugs administered simultaneously to spontaneously hypertensive rats (SHRs). Changes in blood pressure (BP), heart rate (HR), and their variability was determined in pair-fed rats receiving ethanol (5%, w/v), clonidine pellets (10 mg/pellet, s.c.), or their combination for 28 days. Ethanol feeding caused significant decreases and increases in BP and HR, respectively. The time-domain variability indices of BP and HR were also reduced by ethanol. Clonidine produced significant reductions in BP and HR that were evident for only 1-2 days and disappeared thereafter. In rats receiving the combined ethanol and clonidine treatment, hemodynamic changes were identical to those produced by ethanol alone. These findings suggest (i) long-term exposure of SHRs to moderate amounts of ethanol reduces HR variability, possibly due to diminished cardiac vagal modulation, and (ii) the lack of a maintained hypotensive response to clonidine, administered via timed-release pellets, made the evaluation of its chronic interaction with ethanol unfeasible.
Collapse
Affiliation(s)
- Mahmoud M El-Mas
- Department of Pharmacology, School of Medicine, East Carolina University, Greenville, NC 27858, USA
| | | |
Collapse
|