scholarly journals A Blunted Sympathetic Function and an Enhanced Nitrergic Activity Contribute to Reduce Mesenteric Resistance in Hyperthyroidism

2021 ◽  
Vol 22 (2) ◽  
pp. 570
Author(s):  
Laia Cros-Brunsó ◽  
Laura Camacho-Rodríguez ◽  
Ángel Martínez-González ◽  
Pablo Llévenes ◽  
Mercedes Salaices ◽  
...  
Keyword(s):  
Citrate Synthase ◽  
Purinergic Receptor ◽  
Body Weight Gain ◽  
Electrical Field Stimulation ◽  
Alpha Adrenoceptor ◽  
Adrenoceptor Antagonist ◽  
Sympathetic Function ◽  
Vasoconstrictor Response ◽  
Relevant Role ◽  
Male Wistar Rats

We aimed to determine whether an experimental model of hyperthyroidism could alter the function of sympathetic and nitrergic components of mesenteric innervation. For this purpose, male Wistar rats were divided into (1) control rats (CT) and (2) rats infused with L-Thyroxine (HT). Body weight gain and adipose tissue accumulation were lower in HT rats, while systolic blood pressure and citrate synthase activity in the soleus muscle were increased by HT. In segments from the superior mesenteric artery, the application of an electrical field stimulation (EFS) induced a vasoconstrictor response, which was lower in arteries from HT animals. The alpha-adrenoceptor antagonist phentolamine diminished EFS-induced vasoconstriction to a lower extent in HT arteries, while the purinergic receptor antagonist suramin reduced contractile response to EFS only in segments from CT. In line with this, noradrenaline release, tyrosine hydroxylase expression and activation and dopamine β hydroxylase expression were diminished in HT. The unspecific nitric oxide synthase (NOS) inhibitor L-NAME increased EFS-induced vasoconstriction more markedly in segments from HT rats. NO release was enhanced in HT, probably due to an enhancement in neuronal NOS activity, in which a hyperactivation of both PKC and PI3K-AKT signaling pathways might play a relevant role. In conclusion, perivascular mesenteric innervation might contribute to reduce the vascular resistance observed in hyperthyroidism.

Sensitivity of norepinephrine-evoked vasoconstriction to pertussis toxin in the old rat

1998 ◽  
Vol 274 (6) ◽  
pp. R1604-R1612 ◽  
Author(s):  
Alain Robert ◽  
Nguyen N. P. Tran ◽  
Philippe Giummelly ◽  
Jeffrey Atkinson ◽  
Christine Capdeville-Atkinson
Keyword(s):  
Intracellular Calcium ◽  
G Protein ◽  
Pertussis Toxin ◽  
Receptor Activation ◽  
Plasma Norepinephrine ◽  
Adrenoceptor Antagonist ◽  
Vasoconstrictor Response ◽  
High K ◽  
Male Wistar Rats

In male Wistar rats, the in vitro vasoconstrictor response of the perfused tail artery elicited by norepinephrine or serotonin decreased with age (24 mo old vs. 3 mo old), whereas the fluorescent signal (fura 2) produced by intracellular calcium ([Formula: see text]) mobilization increased. Both vasoconstriction and the increase in intracellular calcium concentration elicited by a high-K+, depolarizing solution were unaffected by aging. Pertussis toxin, a G protein inhibitor, had no effect on vasoconstriction induced by high K+ but diminished vasoconstrictor responses to norepinephrine in 3- and 12-mo-old animals but not in 24-mo-old animals. Pertussis toxin had no effect on[Formula: see text] mobilization. The sensitivity of receptor activation to pertussis toxin in tail arteries from 24-mo-old animals was restored by pretreatment with the α-adrenoceptor antagonist nicergoline. Nicergoline had no effect on vasoconstriction induced by high K+. Plasma norepinephrine concentration rose with age; nicergoline had no effect on this rise. We suggest that aging leads to a decrease in the intracellular G protein-modulated amplification of vasoconstriction produced by receptor activation and that this could be linked to the hyperadrenergic state. Ca2+sensitivity can be restored by chronic treatment with an α-adrenoceptor antagonist.

scholarly journals Altered Purinergic Receptor Sensitivity in Type 2 Diabetes-Associated Endothelial Dysfunction and Up4A-Mediated Vascular Contraction

2018 ◽  
Vol 19 (12) ◽  
pp. 3942 ◽  
Author(s):  
Ali Mahdi ◽  
Tong Jiao ◽  
Yahor Tratsiakovich ◽  
Jiangning Yang ◽  
Claes-Göran Östenson ◽  
...  
Keyword(s):  
Endothelial Dysfunction ◽  
Endothelial Function ◽  
Vascular Function ◽  
Purinergic Receptor ◽  
Purinergic Signaling ◽  
Mesenteric Arteries ◽  
Vascular Contraction ◽  
Gk Rats ◽  
Vasoconstrictor Response

Purinergic signaling may be altered in diabetes accounting for endothelial dysfunction. Uridine adenosine tetraphosphate (Up4A), a novel dinucleotide substance, regulates vascular function via both purinergic P1 and P2 receptors (PR). Up4A enhances vascular contraction in isolated arteries of diabetic rats likely through P2R. However, the precise involvement of PRs in endothelial dysfunction and the vasoconstrictor response to Up4A in diabetes has not been fully elucidated. We tested whether inhibition of PRs improved endothelial function and attenuated Up4A-mediated vascular contraction using both aortas and mesenteric arteries of type 2 diabetic (T2D) Goto Kakizaki (GK) rats vs. control Wistar (WT) rats. Endothelium-dependent (EDR) but not endothelium-independent relaxation was significantly impaired in both aortas and mesenteric arteries from GK vs. WT rats. Non-selective inhibition of P1R or P2R significantly improved EDR in aortas but not mesenteric arteries from GK rats. Inhibition of A1R, P2X7R, or P2Y6R significantly improved EDR in aortas. Vasoconstrictor response to Up4A was enhanced in aortas but not mesenteric arteries of GK vs. WT rats via involvement of A1R and P2X7R but not P2Y6R. Depletion of major endothelial component nitric oxide enhanced Up4A-induced aortic contraction to a similar extent between WT and GK rats. No significant differences in protein levels of A1R, P2X7R, and P2Y6R in aortas from GK and WT rats were observed. These data suggest that altered PR sensitivity accounts for endothelial dysfunction in aortas in diabetes. Modulating PRs may represent a potential therapy for improving endothelial function.

Effect of stimulation of nucleus raphe dorsalis on carotid blood flow. II. The cat

1985 ◽  
Vol 248 (2) ◽  
pp. R263-R269 ◽  
Author(s):  
P. J. Goadsby ◽  
R. D. Piper ◽  
G. A. Lambert ◽  
J. W. Lance
Keyword(s):  
Intravenous Administration ◽  
Spinal Cord Section ◽  
Homocysteic Acid ◽  
Alpha Adrenoceptor ◽  
Adrenoceptor Antagonist ◽  
Adrenoceptor Blocker ◽  
Raphe Dorsalis ◽  
Constrictor Response ◽  
The Brain ◽  
Stimulation Of

The dorsal raphe nucleus (DRN) and surrounding midbrain of 74 cats were stimulated both electrically and chemically, and carotid flows were measured with electromagnetic flow probes. Stimulation of the DRN caused a frequency-dependent decrease in common carotid vascular resistance, which was abolished by bilateral section of the facial nerve intracranially. Injection of DL-homocysteic acid into the DRN reproduced the effect of electrical stimulation, indicating that the responses arose from excitation of cell bodies within the DRN, not from fibers of passage. The responses were mediated entirely within the brain stem since they remained intact after high spinal cord section. The vasodilator response was blocked by the intravenous administration of the nicotinic ganglion blocker hexamethonium but not by the alpha-adrenoceptor blocker phentolamine. The responses were unaffected by intravenous administration of methysergide but were markedly reduced after depletion of central serotonin by pretreatment with the serotonin depletor, p-chlorophenylalanine. A poststimulus constrictor response was mediated by release of catecholamines from the adrenal medulla and was blocked by the alpha-adrenoceptor antagonist phentolamine. No response involved supracollicular mechanisms since they persisted after decerebration.

Correlation between mRNA levels and functional role of α1-adrenoceptor subtypes in arteries: evidence of α1L as a functional isoform of the α1A-adrenoceptor

2005 ◽  
Vol 289 (5) ◽  
pp. H1923-H1932 ◽  
Author(s):  
Daniel Martí ◽  
Raquel Miquel ◽  
Khalid Ziani ◽  
Regina Gisbert ◽  
M. Dolores Ivorra ◽  
...  
Keyword(s):  
Mesenteric Artery ◽  
Mesenteric Arteries ◽  
Main Role ◽  
Mrna Levels ◽  
Rt Pcr ◽  
Response Curves ◽  
Inhibitory Potency ◽  
Adrenoceptor Antagonist ◽  
Relevant Role

The mRNA levels for the three α1-adrenoceptor subtypes, α1A, α1B, and α1D, were quantified by real-time RT-PCR in arteries from Wistar rats. The α1D-adrenoceptor was prominent in both aorta (79.0%) and mesenteric artery (68.7%), α1A predominated in tail (61.7%) and small mesenteric artery (73.3%), and both α1A- and α1D-subtypes were expressed at similar levels in iliac artery. The mRNA levels of the α1B-subtype were a minority in all vessels (1.7–11.1%). Concentration-response curves of contraction in response to phenylephrine or relaxation in response to α1-adrenoceptor antagonists on maximal sustained contraction induced by phenylephrine were constructed from control vessels and vessels pretreated with 100 μmol/l chloroethylclonidine (CEC) for 30 min. The significant decrease in the phenylephrine potency observed after CEC treatment together with the inhibitory potency displayed by 8-{2-[4-(2-methoxyphenyl)-1-piperazinyl]-8-azaspiro ( 4 , 5 ) decane-7-dionedihydrochloride} (BMY-7378, an α1D-adrenoceptor antagonist) confirm the relevant role of α1D-adrenoceptors in aorta and iliac and proximal mesenteric arteries. The potency of 5-methylurapidil (an α1A-adrenoceptor antagonist) and the changes in the potency of both BMY-7378 and 5-methylurapidil after CEC treatment provided evidence of a mixed population of α1A- and α1D-adrenoceptors in iliac and distal mesenteric arteries. The low potency of prazosin (pIC50 < 9) as well as the high 5-methylurapidil potency in tail and small mesenteric arteries suggest the main role of α1A/α1L-adrenoceptors with minor participation of the α1D-subtype. The mRNA levels and CEC treatment corroborated this pattern and confirmed that the α1L-adrenoceptor could be a functional isoform of the α1A-subtype.

Practical Application of Microcapsulation for Toxicity Studies Using Bromodichloromethane as a Model Compound

1989 ◽  
Vol 8 (6) ◽  
pp. 1177-1187
Author(s):  
Y. Aida ◽  
M. Ando ◽  
K. Takada ◽  
J Momma ◽  
H. Yoshimoto ◽  
...  
Keyword(s):  
Body Weight ◽  
Olive Oil ◽  
Body Weight Gain ◽  
Male Rats ◽  
Toxicity Tests ◽  
Bile Duct Proliferation ◽  
Volatile Chemicals ◽  
Feeding Study ◽  
Toxicity Studies ◽  
Male Wistar Rats

Gelatin-starch syrup (food grade) microcapsulation was applied for toxicology studies of bromodichloromethane (BDCM). BDCM concentrations were stable for 120 days in the microcapsules and for 9 months when incorporated in the powder diet. BDCM concentration in the blood following the administration of microcapsules in olive oil suspension was retained at higher levels than when BDCM was administered as olive oil solution. Subsequently, the microcapsules were mixed in powder diet and were given at concentrations of microcapsulated BDCM of 0, 0.024, 0.072, and 0.215% to groups of 7 male Wistar rats for 1 month. For comparison, BDCM dissolved in olive oil was administered by gavage to groups of 7 male rats for 1 month at dosage levels adjusted to those in the feeding study (0, 20, 60, and 180 mg/kg body weight). Suppression of body weight gain was seen in the high-dosage groups in both the feeding and the gavage studies and was more severe in the former. Similar histopathologic lesions in the liver were shown in both studies, including vacuolization, swelling, and single necrosis of liver cells. Hepatic cord irregularity and bile duct proliferation were observed in the feeding study but not the gavage study. Serum biochemical changes, such as decreases in glucose, triglyceride, and cholinesterase levels, which reflected the histopathologic findings in the liver, were also observed in both studies. Accordingly, the microcapsulation process was proved to pose no qualitative toxic effects on toxicity of BDCM in short-term toxicity studies. It is concluded that the application of microcapsulation is useful for toxicity tests of volatile chemicals when incorporated into food.

scholarly journals The Interplay of Mitochondrial Oxidative Stress and Endoplasmic Reticulum Stress in Cardiovascular Fibrosis in Obese Rats

Antioxidants ◽  
2021 ◽  
Vol 10 (8) ◽  
pp. 1274
Author(s):  
Francisco V. Souza-Neto ◽  
Sara Jiménez-González ◽  
Beatriz Delgado-Valero ◽  
Raquel Jurado-López ◽  
Marie Genty ◽  
...  
Keyword(s):  
Oxidative Stress ◽  
Endoplasmic Reticulum ◽  
Er Stress ◽  
Control Diet ◽  
Ang Ii ◽  
Mitochondrial Oxidative Stress ◽  
Relevant Role ◽  
Male Wistar Rats ◽  
Cardiovascular Fibrosis ◽  
Stress Activation

We have evaluated the role of mitochondrial oxidative stress and its association with endoplasmic reticulum (ER) stress activation in the progression of obesity-related cardiovascular fibrosis. MitoQ (200 µM) was orally administered for 7 weeks to male Wistar rats that were fed a high-fat diet (HFD, 35% fat) or a control diet (CT, 3.5% fat). Obese animals presented cardiovascular fibrosis accompanied by increased levels of extracellular matrix proteins and profibrotic mediators. These alterations were associated with ER stress activation characterized by enhanced levels (in heart and aorta vs. CT group, respectively) of immunoglobulin binding protein (BiP; 2.1-and 2.6-fold, respectively), protein disulfide-isomerase A6 (PDIA6; 1.9-fold) and CCAAT-enhancer-binding homologous protein (CHOP; 1.5- and 1.8-fold, respectively). MitoQ treatment was able to prevent (p < 0.05) these modifications at cardiac and aortic levels. MitoQ (5 nM) and the ER stress inhibitor, 4-phenyl butyric acid (4 µM), were able to block the prooxidant and profibrotic effects of angiotensin II (Ang II, 10−6 M) in cardiac and vascular cells. Therefore, the data show a crosstalk between mitochondrial oxidative stress and ER stress activation, which mediates the development of cardiovascular fibrosis in the context of obesity and in which Ang II can play a relevant role.

Effect of stimulation of nucleus raphe dorsalis on carotid blood flow. I. The monkey

1985 ◽  
Vol 248 (2) ◽  
pp. R257-R262 ◽  
Author(s):  
P. J. Goadsby ◽  
R. D. Piper ◽  
G. A. Lambert ◽  
J. W. Lance
Keyword(s):  
Facial Nerve ◽  
External Carotid ◽  
Blood Flows ◽  
Beta Adrenoceptor ◽  
Alpha Adrenoceptor ◽  
Adrenoceptor Antagonist ◽  
Muscarinic Cholinergic ◽  
Raphe Dorsalis ◽  
Carotid Circulation ◽  
Stimulation Of

The dorsal raphe nucleus (DRN) and surrounding midbrain of 16 anaesthetized monkeys were stimulated electrically, and carotid blood flows were measured with electromagnetic flow probes. Stimulation of the DRN caused a frequency-dependent decrease (vasodilatation) in both internal and external carotid vascular resistance, which was abolished in both circulations by bilateral section of the facial nerve intracranially. These vasodilator responses were unaltered by intravenous administration of muscarinic cholinergic or by alpha- or beta-adrenoceptor antagonists. A postdilatation constrictor response, observed in the external carotid circulation, was blocked by the alpha-adrenoceptor antagonist phentolamine. It is concluded that projections of the DRN through the greater superficial petrosal branch of the facial nerve mediate vasodilatation in both internal and external carotid circulations.

Nitric oxide modulates arteriolar responses to increased sympathetic nerve activity

1996 ◽  
Vol 271 (3) ◽  
pp. H860-H869 ◽  
Author(s):  
G. P. Nase ◽  
M. A. Boegehold
Keyword(s):  
Nitric Oxide ◽  
Sympathetic Nerve ◽  
Sympathetic Nerve Activity ◽  
Nerve Activity ◽  
Nitric Oxide Synthase Inhibitor ◽  
Alpha Adrenoceptor ◽  
Adrenoceptor Antagonist ◽  
Endogenous Nitric Oxide ◽  
Synthase Inhibitor ◽  
Oxide Synthase

The purpose of this study was to determine whether arteriolar responses to increased sympathetic nerve activity are limited by the actions of endogenous nitric oxide. Intravital microscopy was used to examine diameter responses of small feed arteries (SFA), first-order arterioles (1A) and second-order arterioles (2A) to perivascular sympathetic nerve stimulation in the superfused rat small intestine. Stimulation induced a frequency-dependent constriction in all vessel types that was completely abolished by the alpha-adrenoceptor antagonist phentolamine (10(-6) M). In SFA and 1A, the magnitude of sympathetic constriction was increased significantly in the presence of the nitric oxide synthase inhibitor NG-monomethyl-L-arginine(L-NMMA, 10(-4) M). In SFA (n = 7), stimulation at 3, 8, and 16 Hz induced constrictions of 11 +/- 1, 28 +/- 4, and 42 +/- 3%, respectively, under the normal superfusate vs. 28 +/- 3, 46 +/- 5, and 76 +/- 3% in the presence of L-NMMA. For 1A (n = 7), stimulation induced constrictions of 10 +/- 1, 27 +/- 4, and 37 +/- 3% under the normal superfusate vs. 24 +/- 2, 47 +/- 3, and 72 +/- 4% in the presence of L-NMMA. The effect of L-NMMA on sympathetic constriction in SFA (n = 7) was completely reversed by the additional presence of 5 x 10(-3) M L-arginine in the superfusate. These results suggest that endogenous nitric oxide activity can attenuate sympathetic neurogenic constriction in the intestinal microvasculature.

Evidence for existence of postjunctional alpha 1- and alpha 2-adrenoceptors in cat pulmonary vascular bed

1985 ◽  
Vol 249 (4) ◽  
pp. H891-H898
Author(s):  
A. L. Hyman ◽  
P. J. Kadowitz
Keyword(s):  
Adrenergic Nerve ◽  
Alpha Adrenoceptor ◽  
Adrenoceptor Antagonist ◽  
Vascular Bed ◽  
Alpha Adrenoceptor Agonists ◽  
Adrenoceptor Blocker ◽  
Adrenoceptor Agonists ◽  
Uk 14,304 ◽  
6 Hydroxydopamine ◽  
Pulmonary Vascular Bed

The subtypes of postjunctional alpha-adrenoceptors in the feline pulmonary vascular bed were studied using selective alpha-adrenoceptor agonists and antagonists. Under conditions of controlled pulmonary blood flow and constant left atrial pressure, intralobar injections of the alpha 1-adrenoceptor agonists, phenylephrine and methoxamine, and the alpha 2-adrenoceptor agonists, UK 14,304 and BHT 933, increased lobar arterial pressure in a dose-related manner. Prazosin, an alpha 1-adrenoceptor antagonist, reduced responses to phenylephrine and methoxamine to a greater extent than responses to UK 14,304 and BHT 933. Yohimbine, an alpha 2-adrenoceptor blocker, decreased responses to UK 14,304 and BHT 933 without altering responses to phenylephrine or methoxamine. The same pattern of blockade was observed in animals pretreated with 6-hydroxydopamine, an agent that destroys the integrity of adrenergic nerve terminals. However, in propranolol-treated animals, prazosin antagonized responses to phenylephrine and methoxamine without altering responses to UK 14,304 or BHT 933, and the selectivity of the blocking effects of yohimbine were preserved. Responses to intralobar injections of norepinephrine were markedly decreased by prazosin, whereas yohimbine had only a small effect. These data suggest the presence of both postjunctional alpha 1- and alpha 2-adrenoceptors mediating vasoconstriction in the pulmonary vascular bed. These results also indicate that the vasoconstrictor responses to injected norepinephrine in the cat pulmonary vascular bed are due mainly to activation of alpha 1-adrenoceptors.

Sign in / Sign up

Export Citation Format

Share Document