Bioassay by cross-perfusion for circulating inotropic factor in hypertension

1988 ◽  
Vol 254 (2) ◽  
pp. H230-H237
Author(s):  
H. W. Overbeck
Keyword(s):  
Normal Male ◽  
Response Curves ◽  
Humoral Factors ◽  
Inotropic Effects ◽  
Arteriolar Resistance ◽  
Effective Doses ◽  
Vascular Beds ◽  
Alpha Chloralose ◽  
Minimal Resistance

To study inotropic effects of blood from one-kidney, one-clip (1K,1C) rats with early (less than 7 days) or chronic (greater than 4 wk) benign hypertension, we assessed arteriolar resistance and norepinephrine (NE) responses in vascularly isolated, innervated assay hindlimb vascular beds of alpha-chloralose-anesthetized, normal male recipient rats. Hindlimbs were cross-perfused (2 ml/min) with blood from anesthetized donor rats with limb outflow returned to the donor rat. Perfusion pressure was monitored. Complete NE (injected intra-arterially) dose-response curves in limbs perfused with donor blood from nine early 1K,1C rats, compared with nine appropriate normotensive control donor rats, indicated unchanged thresholds, 50% effective doses, and maximal responses. Curves in limbs perfused with blood from 10 chronic 1K,1C, compared with 10 appropriate controls, suggested small (P less than 0.02) leftward shifts. Decreases (P less than 0.01) in maximal responses were also observed. Limb resting resistance and minimal resistance (sodium nitroprusside) did not rise, even after 4-5 h of cross-perfusion. These results provide no evidence in early 1K,1C and little evidence in chronic 1K,1C that humoral factors, including ouabainlike inhibitors, evoke physiologically significant inotropic effects in arterioles in vivo.

Arteriolar responses to norepinephrine and ouabain in early 1-kidney, 1-clip hypertension in rats

1985 ◽  
Vol 249 (4) ◽  
pp. H851-H858
Author(s):  
H. W. Overbeck
Keyword(s):  
Dose Response ◽  
Response Curve ◽  
Response Curves ◽  
Sodium Potassium ◽  
Inotropic Effects ◽  
Arteriolar Wall ◽  
Vascular Beds ◽  
Normotensive Control

We assessed the role of putative circulating ouabainlike factors on in vivo arteriolar function in rats with very early (less than or equal to 7 days, mean 3 days), benign, one-kidney, one-clip (1K1C) hypertension. Thus we measured vascular responses in vasodilated (nitroprusside or adenosine), vascularly isolated, innervated hindlimb vascular beds of chloralose-anesthetized 1K1C rats perfused with their own blood at 1 ml/min. Complete dose-response curves to norepinephrine in 19 1K1C compared with 25 uninephrectomized (1K) normotensive control rats showed unchanged thresholds and 50% effective dosages. Magnitude of ouabain-induced leftward shifts of the dose-response curve in 29 1K1C and 30 1K rats were similar. In 1K1C, compared with 1K, limb resting resistance was elevated by 45% (P less than 0.001), and limb resistance at maximal vasodilation was elevated by 15% (P less than 0.02). These results provide no evidence in this form and stage of hypertension that humoral ouabainlike inhibitors of the sodium-potassium pump evoke physiologically significant inotropic effects in arterioles in vivo. However, the results suggest that significant increases in arteriolar wall-to-lumen ratio occur in the earliest stages (3 days) of hypertension and probably contribute to the elevated resistance.

Histamine tachyphylaxis in canine airways despite prostaglandin synthesis inhibition

1988 ◽  
Vol 65 (5) ◽  
pp. 1944-1949 ◽  
Author(s):  
P. J. Antol ◽  
S. J. Gunst ◽  
R. E. Hyatt
Keyword(s):  
Smooth Muscle ◽  
Dose Response ◽  
Prostaglandin Synthesis ◽  
Response Curves ◽  
Synthesis Inhibition ◽  
High Concentrations ◽  
Alpha Chloralose ◽  
Prostaglandin Synthesis Inhibitors

Tachyphylaxis to aerosolized histamine was studied in dogs anesthetized with thiamylal after pretreatment with prostaglandin synthesis inhibitors. Three consecutive histamine dose-response curves were obtained in nine dogs pretreated with 5 mg/kg indomethacin; two of these nine were also pretreated with 10 mg/kg indomethacin. Seven of the nine dogs were pretreated with 4 mg/kg sodium meclofenamate; four of these seven were also pretreated with 12 mg/kg. All dogs had tachyphylaxis at high concentrations of histamine regardless of inhibitor used. Pretreatment with indomethacin while the dogs were under alpha-chloralose-urethan anesthesia gave similar results. Histamine tachyphylaxis was also studied both in the presence and in the absence of indomethacin in tracheal smooth muscle strips obtained from seven additional dogs. A decrease in the median effective dose to histamine was observed in the indomethacin-treated strips, but tachyphylaxis to histamine remained. We conclude that prostaglandin synthesis inhibition does not reverse histamine tachyphylaxis either in vivo or in vitro. Thus the mechanism of histamine tachyphylaxis remains unexplained.

TRH and GRF stimulate release of growth hormone through different mechanisms

1986 ◽  
Vol 250 (5) ◽  
pp. E512-E517
Author(s):  
M. Szabo
Keyword(s):  
Growth Hormone ◽  
Response Curves ◽  
Calcium Dependent ◽  
System A ◽  
Effective Doses ◽  
Primary Monolayer ◽  
Plasma Gh ◽  
Primary Monolayer Cultures

Thyrotropin-releasing hormone (TRH) is an effective stimulator of growth hormone (GH) release from cultured adenohypophysial cells of chronically hypothyroid rats in vitro. The present study explored the question of cAMP and calcium mediation of the GH-stimulatory effect of TRH in this system. A maximally stimulatory concentration of TRH was added together with various concentrations of human GH-releasing factor 40 (hGRF-40) whose action is cAMP mediated, or of dibutyryl cAMP (DBcAMP), to primary monolayer cultures of adenohypophysial cells from thyroidectomized rats. The GH responses to the combined addition of TRH with all doses of GRF or DBcAMP were fully additive, causing parallel elevations of the dose-response curves. Whereas the GH response to maximally effective concentrations of hGRF-40 and DBcAMP, added together, was not greater than that to either secretagogue alone, the inclusion of TRH increased the response to a new Emax. The calcium inhibitors, verapamil, EGTA, and CoCl2, markedly suppressed basal GH release and virtually completely blocked the GH response to TRH, suggesting calcium mediation. In chronically hypothyroid, urethan-anesthetized rats, the in vivo effect of the combined administration of maximally effective doses of TRH and GRF on plasma GH levels was also additive. These findings indicate that TRH stimulates GH release in adenohypophysial cells of hypothyroid rats by a cAMP-independent, calcium-dependent mechanism.

Effect of destruction of the vascular endothelium upon pressure/flow relations and endothelium-dependent vasodilatation in resistance beds of spontaneously hypertensive rats

1991 ◽  
Vol 80 (5) ◽  
pp. 463-469 ◽  
Author(s):  
Michael D. Randall ◽  
G. Roger Thomas ◽  
C. Robin Hiley
Keyword(s):  
Spontaneously Hypertensive Rats ◽  
Regression Line ◽  
Hypertensive Rats ◽  
Response Curves ◽  
Pressure Flow ◽  
Spontaneously Hypertensive ◽  
Wistar Kyoto Rats ◽  
Vascular Beds ◽  
Wistar Kyoto

1. Pressure/flow relationships were determined in the in situ blood-perfused superior mesenteric and hindquarters vascular beds of spontaneously hypertensive rats and Wistar-Kyoto normotensive rats before and after destruction of the endothelium with detergent. The effects of indomethacin on the regression of pressure on flow were also investigated in the spontaneously hypertensive rats, as were the endothelium-dependent relaxations in response to carbachol in the mesenteric bed. 2. In the spontaneously hypertensive rats the regression line of pressure on flow in the two vascular beds was both steeper and more elevated than in the Wistar-Kyoto rats, showing that there was greater resistance to flow in the hypertensive animals. Destruction of the endothelium significantly increased the slope of the regression in both Wistar-Kyoto and spontaneously hypertensive rats: the increases in the Wistar-Kyoto rats were 2.4 ± 0.3 fold (mesenteric) and 2.0 ± 0.5 fold (hindquarters) which were comparable with the respective increases of 1.6 ± 0.3 fold and 1.8 ± 0.3 fold in the spontaneously hypertensive rats. 3. Indomethacin (5 mg/kg, intravenously) had no effect on the pressure/flow relations in either of the vascular beds of the spontaneously hypertensive rats. 4. The dose-response curves for the endothelium-dependent vasodilatation in response to carbachol were not significantly different in spontaneously hypertensive and Wistar-Kyoto rats. 5. The results suggest that tonic release of endothelium-derived relaxing factor has similar effects in modulating resistance vessel tone in vivo in both hypertensive and normotensive rats. Further, endothelium-dependent vasodilatation does not appear to be impaired in the mesenteric vasculature in spontaneously hypertensive rats, and there appears to be no significant modulation of mesenteric vascular resistance by tonic release of cyclo-oxygenase products in spontaneously hypertensive rats.

scholarly journals Histamine can be Formed and Degraded in the Human and Mouse Heart

2021 ◽  
Vol 12 ◽  
Author(s):  
Joachim Neumann ◽  
Juliane M. Grobe ◽  
Jacqueline Weisgut ◽  
Hubert G. Schwelberger ◽  
Wieslawa Agnieszka Fogel ◽  
...  
Keyword(s):  
Human Heart ◽  
Histidine Decarboxylase ◽  
Physiological Role ◽  
Right Atrial ◽  
Mouse Heart ◽  
Response Curves ◽  
Metabolizing Enzymes ◽  
Inotropic Effects ◽  
Mammalian Heart

Histamine is metabolized by several enzymes in vitro and in vivo. The relevance of this metabolism in the mammalian heart in vivo is unclear. However, histamine can exert positive inotropic effects (PIE) and positive chronotropic effects (PCE) in humans via H2-histamine receptors. In transgenic mice (H2-TG) that overexpress the human H2 receptor in cardiomyocytes but not in wild-type littermate mice (WT), histamine induced PIE and PCE in isolated left or right atrial preparations. These H2-TG were used to investigate the putative relevance of histamine degrading enzymes in the mammalian heart. Histidine, the precursor of histamine, increased force of contraction (FOC) in human atrial preparations. Moreover, histamine increased the phosphorylation state of phospholamban in human atrium. Here, we could detect histidine decarboxylase (HDC) and histamine itself in cardiomyocytes of mouse hearts. Moreover, our data indicate that histamine is subject to degradation in the mammalian heart. Inhibition of the histamine metabolizing enzymes diamine oxidase (DAO) and monoamine oxidase (MAO) shifted the concentration response curves for the PIE in H2-TG atria to the left. Moreover, activity of histamine metabolizing enzymes was present in mouse cardiac samples as well as in human atrial samples. Thus, drugs used for other indication (e.g. antidepressants) can alter histamine levels in the heart. Our results deepen our understanding of the physiological role of histamine in the mouse and human heart. Our findings might be clinically relevant because we show enzyme targets for drugs to modify the beating rate and force of the human heart.

EXTRAHEPATIC AND EXTRARENAL RENIN INACTIVATION IN THE DOG

1974 ◽  
Vol 60 (2) ◽  
pp. 217-222
Author(s):  
R. FAGARD ◽  
E. FOSSION ◽  
M. CAMPFORTS ◽  
A. AMERY
Keyword(s):  
Blood Vessels ◽  
Pulmonary Circulation ◽  
Plasma Renin ◽  
Glass Container ◽  
Plasma Renin Concentration ◽  
Vascular Beds ◽  
Extrarenal Renin

SUMMARY It was demonstrated previously that renin disappears quickly from the circulation after nephrectomy in the hepatectomized dog. In the present study the plasma renin concentration (PRC) was measured in the efferent and afferent blood vessels of several vascular beds (pulmonary circulation, splanchnic region, spleen, both inferior limbs and pelvis, head) in the anhepatic and in the anhepatic and anephric dog in order to investigate extrarenal and extrahepatic renin inactivation. However, no significant arteriovenous differences in PRC could be traced. The blood of these dogs kept in vitro at 37 °C in a glass container showed no decline in PRC within 3 h of removal. Therefore no specific extrahepatic and extrarenal renin-inactivating mechanism was found which could explain the rapid disappearance of renin from the blood in vivo in the anhepatic and anephric dog.

Integration of in vitro neurotoxicity data with biokinetic modelling for the estimation of in vivo neurotoxicity

2007 ◽  
Vol 26 (4) ◽  
pp. 333-338 ◽  
Author(s):  
Anna Forsby ◽  
Bas Blaauboer
Keyword(s):  
Exposure Period ◽  
Cellular Protein ◽  
In Vitro Toxicity ◽  
Target Tissue ◽  
Receptor Function ◽  
Human Neuroblastoma ◽  
Protein Levels ◽  
Effective Doses

Risk assessment of neurotoxicity is mainly based on in vivo exposure, followed by tests on behaviour, physiology and pathology. In this study, an attempt to estimate lowest observed neurotoxic doses after single or repeated dose exposure was performed. Differentiated human neuroblastoma SH-SY5Y cells were exposed to acrylamide, lindane, parathion, paraoxon, phenytoin, diazepam or caffeine for 72 hours. The effects on protein synthesis and intracellular free Ca2+concentration were studied as physiological endpoints. Voltage operated Ca2 +channel function, acetylcholine receptor function and neurite degenerative effects were investigated as neurospecific endpoints for excitability, cholinergic signal transduction and axonopathy, respectively. The general cytotoxicity, determined as the total cellular protein levels after the 72 hours exposure period, was used for comparison to the specific endpoints and for estimation of acute lethality. The lowest concentration that induced 20% effect (EC 20) obtained for each compound, was used as a surrogate for the lowest neurotoxic level (LOEL) at the target site in vivo. The LOELs were integrated with data on adsorption, distribution, metabolism and excretion of the compounds in physiologically-based biokinetic (PBBK) models of the rat and the lowest observed effective doses (LOEDs) were estimated for the test compounds. A good correlation was observed between the estimated LOEDs and experimental LOEDs found in literature for rat for all test compounds, except for diazepam. However, when using in vitro data from the literature on diazepam's effect on gamma-amino butyric acid (GABA)A receptor function for the estimation of LOED, the correlation between the estimated and experimental LOEDs was improved from a 10 000-fold to a 10-fold difference. Our results indicate that it is possible to estimate LOEDs by integrating in vitro toxicity data as surrogates for lowest observed target tissue levels with PBBK models, provided that some knowledge about toxic mechanisms is known. Human & Experimental Toxicology (2007) 26, 333—338

4-Chloro-m-cresol Triggers Malignant Hyperthermia in Susceptible Swine at Doses Greatly Exceeding Those Found in Drug Preparations

1999 ◽  
Vol 90 (6) ◽  
pp. 1723-1732. ◽  
Author(s):  
Paul A. Iaizzo ◽  
Brooks A. Johnson ◽  
Kaoru Nagao ◽  
William J. Gallagher
Keyword(s):  
Malignant Hyperthermia ◽  
Blood Chemistry ◽  
Response Curves ◽  
End Tidal ◽  
In Vivo Effects ◽  
Higher Doses ◽  
End Tidal Co2 ◽  
Cardiovascular Reactions

Background Chlorocresols are used as preservatives in numerous commercial drugs that have been shown to induce myoplasmic Ca2+ release; the most potent isoform is 4-chloro-m-cresol. The aims of this study were to (1) examine the in vivo effects of 4-chloro-m-cresol on swine susceptible to malignant hyperthermia and (2) contrast in vivo versus in vitro dose-response curves. Methods Susceptible swine (weight: 38.5 kg+/-3.55 kg) were anesthetized and monitored for variations in physiological responses, including end-tidal CO2, heart rate, blood pressure, blood chemistry, and temperatures. In the first animals studied, 4-chloro-m-cresol, at equivalent cumulative doses of 0.14, 0.28, 0.57, 1.14, 2.27, 4.54, and 9.08 mg/kg (n = 3; 12.5, 25, 50, 100, 200, 400, and 800 micromol) were administered, and in a second group, larger doses were used: 1.14, 3.41, 7.95, 17.04 (n = 4), and/or 35.22 (n = 1) mg/kg (100, 300, 700, 1,500, and/or 3,100 micromol). For comparison, in vitro rectus abdominis muscle preparations obtained from normal and susceptible swine were exposed to 4-chloro-m-cresol, at cumulative concentrations of 6.25, 12.5, 25, 50, 100, 200, 400, 800, and 1,600 micromol; standard caffeine and halothane contracture testing was also performed. Results Episodes of malignant hyperthermia were not triggered in response to administration of low doses of 4-chloro-m-cresol, but transient cardiovascular reactions (e.g., tachycardia, arrhythmias, and hypotension) were observed. Subsequently, episodes in these animals were triggered when halothane (0.87; 1 MAC) and succinylcholine (2 mg/kg) were given. Animals administered the higher doses of 4-chloro-m-cresol all had fulminant episodes of malignant hyperthermia that were fatal, when equivalent cumulative concentrations were greater than 1,500 micromol. The levels of 4-chloro-m-cresol in the plasma rapidly decreased: e.g., 5 min postadministration of the 1,500-micromol dose, the mean plasma level was only 52+/-18 micromol (n = 4). Hemolysis was detected following 4-chloro-m-cresol administration at concentrations > 200 micromol. In vitro, muscle from susceptible animals elicited contractures > 200 mg at 50-micromol bath concentrations of 4-chloro-m-cresol (n = 29), whereas normal muscle did not elicit such contractures until bath concentrations were > 800 micromol (n = 10). Conclusions 4-chloro-m-cresol is a trigger of malignant hyperthermia in susceptible swine, but only when serum concentrations are far above those likely to be encountered in humans. A relatively low concentration of 4-chloro-m-cresol, 50 micromol, is sufficient to activate sarcoplasmic [Ca+2] release in vitro (e.g., contractures); this same bolus dose administered in vivo (0.57 mg/kg) has minimal effects due to the rapid decrease in its plasma levels.

scholarly journals Physiologically based kinetic modelling based prediction of in vivo rat and human acetylcholinesterase (AChE) inhibition upon exposure to diazinon

2021 ◽  
Author(s):  
Shensheng Zhao ◽  
Sebastiaan Wesseling ◽  
Bert Spenkelink ◽  
Ivonne M. C. M. Rietjens
Keyword(s):  
Dose Response ◽  
Kinetic Modelling ◽  
Ache Inhibition ◽  
Response Curves ◽  
Alternative Testing ◽  
Dose Response Curves ◽  
Physiologically Based Kinetic Modelling ◽  
Point Of Departure

AbstractThe present study predicts in vivo human and rat red blood cell (RBC) acetylcholinesterase (AChE) inhibition upon diazinon (DZN) exposure using physiological based kinetic (PBK) modelling-facilitated reverse dosimetry. Due to the fact that both DZN and its oxon metabolite diazoxon (DZO) can inhibit AChE, a toxic equivalency factor (TEF) was included in the PBK model to combine the effect of DZN and DZO when predicting in vivo AChE inhibition. The PBK models were defined based on kinetic constants derived from in vitro incubations with liver fractions or plasma of rat and human, and were used to translate in vitro concentration–response curves for AChE inhibition obtained in the current study to predicted in vivo dose–response curves. The predicted dose–response curves for rat matched available in vivo data on AChE inhibition, and the benchmark dose lower confidence limits for 10% inhibition (BMDL10 values) were in line with the reported BMDL10 values. Humans were predicted to be 6-fold more sensitive than rats in terms of AChE inhibition, mainly because of inter-species differences in toxicokinetics. It is concluded that the TEF-coded DZN PBK model combined with quantitative in vitro to in vivo extrapolation (QIVIVE) provides an adequate approach to predict RBC AChE inhibition upon acute oral DZN exposure, and can provide an alternative testing strategy for derivation of a point of departure (POD) in risk assessment.

Abstract 11664: The Identification and Hierarchy of Bone Marrow-Derived Artery-Resident Mesodermal Progenitor Cells and Their Dynamics in Atherosclerosis

Circulation ◽  
2014 ◽  
Vol 130 (suppl_2) ◽  
Author(s):  
Hyun-Jai Cho ◽  
Hyun-Ju Cho ◽  
Yoo-Wook Kwon ◽  
Young-Bae Park ◽  
Hyo-Soo Kim
Keyword(s):  
Bone Marrow ◽  
Progenitor Cells ◽  
Peripheral Circulation ◽  
Humoral Factors ◽  
Cell Property ◽  
Apoe Ko Mice ◽  
Multiplex Cytokine ◽  
Developmental Hierarchy

Background: We recently identified bone marrow (BM)-derived artery resident calcifying progenitor cells. Sca-1+PDGFRα- cells may possess bipotent (osteoblastic/osteoclastic) characteristics. However, the nature of progenitor cells remains elusive. Hypothesis: We investigated developmental hierarchy of progenitor cells and in vivo dynamics in atherosclerosis. Methods and Results: We harvested cells from BM and artery of C57 mice. In BM, Lin-CD29+Sca-1+PDGFRα- cells showed hematopoietic potential and differentiated into osteoclasts (OC). They also possessed mesenchymal stem cell property including osteoblastic (OB) differentiation, suggesting that Sca-1+PDGFRα- cells could be mesodermal progenitor cells. Interestingly, BM-derived artery-resident, clonal Sca-1+PDGFRα- cells maintained bipotency but lost hematopoietic nature. In contrast, Sca-1+PDGFRα+ cells in BM and artery only showed unipotency (OB). When we overexpressed or knocked down PDGFRα, there was no alteration in OB or OC differentiation of Sca-1+PDGFRα- cells and no effect on OB differentiation of Sca-1+PDGFRα+ cells, indicating PDGFRα as a surface marker but not a functional player. In hyperlipidemic ApoE-KO mice compared with control, Sca-1+PDGFRα- cells were less mobilized from BM to peripheral circulation and less infiltrated into atherosclerotic plaque, whereas Sca-1+PDGFRα+ cells were not significantly affected. Multiplex cytokine assay of serum and artery revealed that IL-1β was significantly increased and IL-5 was markedly decreased in atherosclerotic mice. IL-1β decreased the migration of Sca-1+PDGFRα- cells by 5 folds compared with TNFα, and IL-5 increased the migration as much as TNFα. But the migration of Sca-1+PDGFRα+ cells was not altered. These data indicate that atherosclerosis-related humoral factors mainly regulated mesodermal progenitor cells’ dynamics. Conclusion: We demonstrate that Sca-1+PDGFRα- cell is a mesodermal progenitor cell that possesses both hematopoietic and mesenchymal potentials. In atherogenesis, the mobilization and infiltration of Sca-1+PDGFRα- progenitor cells were regulated by IL-1β and IL-5. These data provide a novel mechanism regarding the role of bipotent progenitor cells in atherosclerosis.

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