scholarly journals Control of vascular tone in notothenioid fishes is determined by phylogeny, not environmental temperature

2001 ◽  
Vol 280 (4) ◽  
pp. R1197-R1205 ◽  
Author(s):  
S. Egginton ◽  
M. E. Forster ◽  
W. Davison
Keyword(s):  
Vascular Tone ◽  
Vascular Reactivity ◽  
Environmental Temperature ◽  
Antarctic Fish ◽  
Sister Group ◽  
Maximal Response ◽  
Control Mechanisms ◽  
Dissostichus Mawsoni ◽  
Modest Contribution ◽  
Branchial Arteries

We examined potential vasomotor control mechanisms in an Antarctic fish ( Trematomus bernacchii; usual core temperature approximately −1°C), comparing sensitivity to agonists by means of the cumulative dose response and potency with reference to depolarization by 50 mM KCl. In efferent branchial arteries, norepinephrine (NE) produced ∼20% of the maximal KCl tension and ∼40% in the presence of 10−3M sotalol, suggesting a modest contribution of α- and β-adrenergic tonus [half-maximal response (pEC50) = 6.29 ± 0.37 M]. Carbachol (CBC) and serotonin (5-HT) had different sensitivities (pEC50 = 4.50 ± 0.40 and 6.82 ± 0.08 M, respectively) but similar potencies (21.6 ± 11.1 and 31.1 ± 5.3% of KCl). A related species from warmer waters around New Zealand, Paranotothenia angustata, had similar vascular reactivity for NE (pEC50 = 5.48 ± 0.31 M), CBC (pEC50 = 4.94 ± 0.22 M), and methysergide-sensitive vasoconstriction with 5-HT (pEC50 = 6.22 ± 0.40 M). Agonist potencies were 9, 65, and 45% that of KCl, respectively. Bovichtus variegatus, a member of the phylogenetic sister group to the notothenioids, also gave broadly similar responses. In contrast, Dissostichus mawsoni, a pelagic Antarctic notothenioid, showed a dominance of vasodilatation over vasoconstriction, with sensitive isoprenaline (pEC50 = 6.66 ± 0.05 M) but weak serotonergic (5.2 ± 1.5% KCl) responses. The unusual dominance of serotonergic control appears to be primarily a consequence of evolutionary lineage rather than low environmental temperature, but the pattern may be modified according to functional demand.

Renal hemodynamics and vascular reactivity in canine DOCA-salt hypertension

1988 ◽  
Vol 255 (4) ◽  
pp. R563-R568
Author(s):  
J. L. Goering ◽  
P. C. Raich ◽  
B. G. Zimmerman
Keyword(s):  
Blood Flow ◽  
Renal Blood Flow ◽  
Vascular Tone ◽  
Vascular Reactivity ◽  
Control Period ◽  
Indwelling Catheter ◽  
Alpha Adrenoceptor ◽  
Arterial Blood ◽  
Salt Hypertension ◽  
Renal Vascular

Because of the potential role that the kidney may play in deoxycorticosterone acetate (DOCA)-salt hypertension, changes in renal blood flow, renal vascular reactivity, and renal adrenergic vascular tone were followed in the conscious instrumented dog. DOCA-salt was administered daily after obtaining control measurements. Systemic mean arterial blood pressure (MAP) was monitored with an indwelling catheter, renal blood flow (RBF) was measured electromagnetically using an implanted blood flow probe, and drugs were administered intrarenal arterially through an indwelling renal artery catheter. During the first week of DOCA-salt administration MAP increased from 106 +/- 3 to 118 +/- 2 mmHg and at week 2 to 123 +/- 2 mmHg (P less than 0.01). RBF increased from 275 +/- 32 to 336 +/- 34 during week 1 (P less than 0.05) and to 324 +/- 29 ml/min during week 2. The log ED50 of norepinephrine administered intra-arterially decreased from 1.66 +/- 0.114 to 1.48 +/- 0.091 and 1.41 +/- 0.067 ng/ml (P less than 0.05), and of angiotensin II from 2.58 +/- 0.072 to 2.31 +/- 0.09 (P less than 0.05) and 2.38 +/- 0.05 pg/ml, during weeks 1 and 2, respectively. There was, however, no increase in adrenergic vascular tone as determined by the change in RBF obtained with the intra-arterial infusion of alpha-adrenoceptor antagonists. These experiments indicate that RBF is not compromised in canine DOCA-salt hypertension, and renal adrenergic tone is no greater in the hypertensive than in the normotensive control period.

Androgen-receptor defect abolishes sex differences in nitric oxide and reactivity to vasopressin in rat aorta

2001 ◽  
Vol 91 (6) ◽  
pp. 2602-2610 ◽  
Author(s):  
John N. Stallone ◽  
Ronald L. Salisbury ◽  
Clifford T. Fulton
Keyword(s):  
Nitric Oxide ◽  
Androgen Receptor ◽  
Methyl Ester ◽  
Thoracic Aorta ◽  
Vascular Reactivity ◽  
Rat Aorta ◽  
Maximal Response ◽  
Maximal Contraction ◽  
Rat Thoracic Aorta ◽  
Recessive Defect

Contractions of rat thoracic aorta to vasopressin (VP) are threefold higher in females (F) than in males (M), primarily because nitric oxide (NO) attenuation of contraction is greater in M. To determine the role of the androgen receptor (AR) in this mechanism, vascular reactivity to VP was examined in thoracic aorta of the testicular-feminized male (Tfm) rat, which has an X-linked, recessive defect in AR function in affected M. Maximal contraction of normal aortas to VP was fourfold higher in F (4,128 ± 291 mg/mg ring wt) than in M (971 ± 133 mg); maximal response of Tfm (3,967 ± 253 mg) was similar to that of normal F. N G-nitro-l-arginine methyl ester increased maximal response to VP threefold in M but had no effect in F or Tfm. In contrast, maximal contraction of normal aortas to phenylephrine was 43% higher in M (4,011 ± 179 mg) than in F (2,809 ± 78 mg); maximal response of Tfm (2,716 ± 126 mg) was similar to that of normal F. N G-nitro-l-arginine methyl ester increased maximal response to phenylephrine by >50% in F and Tfm but had no effect in M. Maximal contractile response to 80 mM KCl did not differ among M, F, or Tfm. Thus androgens and normal vascular AR function are important in the greater NO-mediated attenuation of reactivity to VP in M than in F rat aorta, which may involve specific modulation of endothelial VP signal transduction pathways and NO release by androgens. These data also establish the importance of the Tfm rat as a model to study the effects of androgens on cardiovascular function.

Sexual dimorphism in vasopressin-induced contraction of rat aorta

1991 ◽  
Vol 260 (2) ◽  
pp. H453-H458 ◽  
Author(s):  
J. N. Stallone ◽  
J. T. Crofton ◽  
L. Share
Keyword(s):  
Estrous Cycle ◽  
Vascular Reactivity ◽  
Rat Aorta ◽  
Isometric Tension ◽  
Female Rats ◽  
Male Rats ◽  
Maximal Response ◽  
Sprague Dawley ◽  
Tension Development ◽  
Sprague Dawley Rats

Previously, we reported that, in the rat, pressor responsiveness to vasopressin (VP) is higher in males than in females during most phases of the estrous cycle. To explore the role of the vasculature in this phenomenon, we examined vascular reactivity to VP in thoracic aortas of male rats and female rats during each phase of the estrous cycle. Aortic rings were prepared from age-matched male and female Sprague-Dawley rats and mounted for isometric tension recording. Maximal response of female aortas to VP (4,246 +/- 163 mg/mg ring dry wt) was more than twice (P less than 0.001) that of male aortas (1,877 +/- 215 mg/mg ring wt). Sensitivity of female aortas to VP was substantially higher (P less than 0.001) than that of male aortas (EC50: 10.9 +/- 0.7 vs. 19.0 +/- 1.6 nM, respectively). Maximal rate of tension development (dT/dtmax) during contraction with VP was nearly twofold higher (P less than 0.01) in female aortas (536 +/- 23 mg/min) than in male aortas (300 +/- 19 mg/min). Maximal response, sensitivity, and dT/dtmax of female aortas did not vary significantly during the estrous cycle. Maximal response of female aortas to phenylephrine (PE; 1,251 +/- 93 mg/mg ring wt) was half that (P less than 0.001) of male aortas (2,546 +/- 194 mg/mg ring wt); sensitivity to PE did not differ significantly (EC50: 0.33 +/- 0.02 vs. 0.38 +/- 0.06 microM, respectively).(ABSTRACT TRUNCATED AT 250 WORDS)

scholarly journals Effect of Betanin, a Beetroot Component, on Vascular Tone in Isolated Porcine Arteries

2020 ◽  
Vol 33 (4) ◽  
pp. 305-309
Author(s):  
Masashi Tawa ◽  
Takayoshi Masuoka ◽  
Yuka Yamashita ◽  
Katsuya Nakano ◽  
Takaharu Ishibashi
Keyword(s):  
Blood Pressure ◽  
Coronary Arteries ◽  
Vascular Tone ◽  
Vascular Reactivity ◽  
Pulmonary Arteries ◽  
Prostaglandin F2α ◽  
Blood Pressure Lowering ◽  
Blood Pressure Lowering Effect ◽  
Independent Manner ◽  
Pressure Lowering

Abstract BACKGROUND Beetroot has attracted much attention because of its blood pressure-lowering properties. Although beetroot contains various nutritional compounds, including inorganic nitrate, some of their physiological properties are not fully understood. In this study, we examined whether betanin, a beetroot component, has a regulatory effect on vascular tone. METHODS Mechanical responses of isolated porcine coronary, mesenteric, and pulmonary arteries were assessed by organ chamber technique. In some cases, the vascular reactivity was observed in the presence of a physiological concentration of betanin (10 µM). RESULTS Betanin did not induce vasorelaxation at physiological concentrations both in endothelium-intact and -denuded coronary, mesenteric, and pulmonary arteries. The endothelium-dependent agonists, bradykinin and A23187 induced vasorelaxation of endothelium-intact coronary arteries, both of which were not affected by exposure to betanin. Likewise, endothelium-independent vasorelaxation induced by sodium nitrite and sodium nitroprusside was also not affected by the presence of betanin. In addition, exposure of endothelium-intact coronary arteries to betanin did not attenuate prostaglandin F2α- and endothelin-1-induced vasocontraction. CONCLUSIONS These findings suggest that betanin does not have a vasorelaxant activity. It is unlikely that betanin is a component directly responsible for the beetroot-induced acute blood pressure-lowering effect in a nitrate-independent manner.

Effects of reserpine on water, cation, and norepinephrine contents of cardiovascular tissues of normotensive dogs

1977 ◽  
Vol 55 (2) ◽  
pp. 206-211 ◽  
Author(s):  
Yukio Komatsu ◽  
George Constantopoulos ◽  
Jolanta Gutkowska ◽  
Jose-Manuel Rojo-Ortega ◽  
Jacques Genest
Keyword(s):  
Vascular Tone ◽  
Vascular Reactivity ◽  
Sodium Potassium ◽  
Arterial Blood ◽  
Cardiovascular Tissues ◽  
Norepinephrine Content ◽  
The Mean ◽  
Calcium And Magnesium ◽  
Plasma Magnesium ◽  
Potassium Magnesium

Six adult male mongrel dogs were treated orally with reserpine (0.03 mg/kg) for 6 weeks, after which time the arterial tissue content of water, cations (sodium, potassium, magnesium, and calcium), and norepinephrine was determined and compared with those of six untreated dogs. Reserpine administration resulted in sustained decreases in the mean arterial blood pressure and heart rate, and the arterial tissues of the treated dogs contained less potassium, calcium, and magnesium, the last-named being affected most, but the sodium remained the same. Arterial norepinephrine content was significantly decreased. There was a slight but significant increase in plasma magnesium, without any noticeable changes in other plasma cations. The reduction in the arterial magnesium by reserpine may help to regulate vascular tone and (or) vascular reactivity.

scholarly journals The influence of testosterone upon vascular reactivity

2004 ◽  
pp. 29-37 ◽  
Author(s):  
RD Jones ◽  
T Hugh Jones ◽  
KS Channer
Keyword(s):  
Animal Studies ◽  
Vascular Tone ◽  
Vascular Reactivity ◽  
Coronary Vascular Tone ◽  
Increased Sensitivity ◽  
Flow Through ◽  
Artery Disease ◽  
Partially Occluded ◽  
Regulation Of Vascular Tone ◽  
Pathogenic Process

Recent clinical studies have reported that testosterone therapy reduces myocardial ischaemia in men with coronary artery disease, and the beneficial modulation of coronary vascular tone by testosterone has been proposed as an effector mechanism. Maintenance of a correct response to vasoconstrictive and vasodilatory agents is essential in the control of vascular tone. Endothelial dysfunction, most commonly manifested through an elevation in vascular tone, is implicated as an initiating factor in conditions such as hypertension and atherosclerosis. Increased sensitivity to vasoconstrictive stimuli is also proposed in the development of heart failure and hypertensive vascular remodelling, while increased coronary vascular reactivity to vasoconstrictive factors is likely further to restrict coronary blood flow through the partially occluded atherosclerotic vessel. Reduced vasodilatation and enhanced vasoconstriction can also lead to vasospasm and exacerbation of anginal symptoms. Testosterone is well known to elicit direct vasodilatation, but its influence upon responses induced by other vasoactive agents is less coherent, and may depend upon the underlying pathogenic process or gender. The aim of this review is to present the data obtained from both the patient and animal studies conducted to date, to ascertain any influence testosterone may have upon the regulation of vascular tone.

scholarly journals The influence of environmental temperatures on farrowing rates and litter sizes in South African pig breeding units

2014 ◽  
Vol 81 (1) ◽  
Author(s):  
Leana Janse van Rensburg ◽  
Brian T. Spencer
Keyword(s):  
South African ◽  
Temperature Control ◽  
Environmental Temperature ◽  
Control Mechanisms ◽  
Ambient Temperatures ◽  
Commercial Breeding ◽  
Weather Stations ◽  
Main Determinants ◽  
Environmental Temperatures ◽  
Farrowing Rate

The reproductive performance of pigs is one of the main determinants of the profit farmers make from pig production. This study was undertaken to describe whether periods of high environmental temperature have an effect on the farrowing rate, litter sizes and number of stillbirths in commercial breeding units in South Africa. Data were collected weekly from four commercial breeding units with good records from December 2010 to August 2012. These data included the number of sows mated, number of sows farrowed and number of piglets born alive, as well as the number of stillbirths. Note was also taken of whether environmental temperature control mechanisms were employed. Temperature data from weather stations within 100 km of the breeding units were obtained from the South African Weather Service. In all breeding units a decrease in farrowing rate following mating during severe average temperatures (> 30 °C) when compared to the farrowing rate following mating during mild average temperatures (< 22 °C) was observed. When mating occurred at higher temperatures, the resultant litter size was marginally decreased in the breeding units that did not employ environmental temperature control, but was unaffected in the breeding units that did. In all four breeding units the trend was for the average number of piglets born alive to increase as the environmental temperature around the time of farrowing increased and the trend in three of the four breeding units was for the percentage of stillbirths per litter to decrease with increased temperature around the time of farrowing. The most significant observation in this study was the trend for farrowing rates to decrease following inseminations during times of high ambient temperatures (> 30 °C). Environmental temperature control did not negate this effect, but the breeding units employing the environmental temperature control did show higher average farrowing rates overall.

RhoA/Rho kinase and nitric oxide modulate the agonist-induced pulmonary artery diameter response time

2002 ◽  
Vol 282 (3) ◽  
pp. H990-H998 ◽  
Author(s):  
Christa Boer ◽  
Peter J. W. van der Linden ◽  
Gert Jan Scheffer ◽  
Nico Westerhof ◽  
Jaap J. de Lange ◽  
...  
Keyword(s):  
Nitric Oxide ◽  
Smooth Muscle ◽  
Response Time ◽  
Vascular Reactivity ◽  
Pulmonary Arteries ◽  
Rho Kinase ◽  
Maximal Response ◽  
Kinase Inhibition ◽  
Pulmonary Vasodilation ◽  
Rate Determining Step

We studied the amplitude and response time (RT; time to 50% of maximal response) of pulmonary vasoreactivity and investigated whether the characteristics of pulmonary vasoreactivity could be modulated by endothelium removal, nitric oxide (NO) synthase inhibition [ N G-nitro-l-arginine (l-NNA)], RhoA activation [lysophosphatidic acid (LPA)] and Rho kinase inhibition (Y-27632). Slow acetylcholine-induced pulmonary vasodilation (262 ± 5 s) was not due to the RT of endothelial NO release (45–55 s) and was always longer than RT in renal arteries (15 ± 4 s). The rate-determining step is located in the smooth muscle cells. This was confirmed by the existing differences between the RT of the NO solution and KCl-induced renal and pulmonary vasoreactivity in endothelium-denuded arteries. We found that the pulmonary contractile amplitude increases and the RT decreases byl-NNA or LPA. In contrast, Y-27632 reduced the contractile amplitude and increased the RT in pulmonary arteries. These phenomena were dependent on the contractile stimulus (phenylephrine or KCl). In conclusion, slow pulmonary vasoreactivity is a smooth muscle cell characteristic that can be enhanced by RhoA and NO or endothelium removal. These effects were counteracted by Rho kinase inhibition. We show a role for RhoA/Rho kinase and NO in the modulation of pulmonary vascular reactivity.

scholarly journals Characterization of Four Liver-Expressed Antimicrobial Peptides from Antarctic Fish and Their Antibacterial Activity

2019 ◽  
Vol 9 (20) ◽  
pp. 4299 ◽  
Author(s):  
Shweta Borkar ◽  
Sondavid Nandanwar ◽  
Jun Lee ◽  
Hak Kim
Keyword(s):  
Antibacterial Activity ◽  
Antimicrobial Peptides ◽  
Antarctic Fish ◽  
Effect Of Temperature ◽  
Dissostichus Mawsoni ◽  
Sytox Green ◽  
Uptake Assay ◽  
The Antarctic ◽  
Β Sheet

Liver-expressed antimicrobial peptides (LEAPs) are cysteine-containing cationic peptides. LEAP-1 and LEAP-2 are eight- and four-cysteine containing antimicrobial peptides found in animals, respectively. LEAP-1 is widely known as antibacterial peptide involved in the innate immunity of fish, but the roles of LEAP-1 and LEAP-2 in Antarctic fish species are unknown. In the present study, we synthesized and characterized novel LEAPs with four and eight cysteine residues, derived from Antarctic notothenioid (Dissostichus mawsoni) and Antarctic eelpout (Lycodichthys dearborni). Circular dichroism spectroscopy of these peptides showed a typical β-sheet conformation. The LEAPs were found to be bactericidal against gram-positive as well as gram-negative bacteria. In the SYTOX green uptake assay, LEAPs did not trigger any significant increase in fluorescence. However, LEAPs competitively bound to DNA and replaced the ethidium bromide (EB) dye. To determine the effect of temperature on the activity of LEAPs, we evaluated the antibacterial activity against Listeria monocytogenes at 5, 15, 25, and 35 °C. The results showed that the antibacterial activity of LEAPs increased with a decrease in temperature, which may indicate that the Antarctic fish LEAP are evolutionarily adapted. Taken together, our results suggest that novel Antarctic LEAPs are bactericidal peptides with the likely mode of action being DNA binding and may be evolved to adapt to cold temperature.

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