An Investigation of the Prolonged Pressor Response to Renin in the Nephrectomized Rat

1976 ◽  
Vol 51 (s3) ◽  
pp. 151s-153s ◽  
Author(s):  
G. W. Boyd
Keyword(s):  
Blood Pressure ◽  
Dose Response ◽  
Pressor Response ◽  
Pressure Increase ◽  
Angiotensin I ◽  
Response Curves ◽  
Blood Pressure Increase ◽  
Dose Response Curves

1. In an investigation of the prolonged pressor response to renin that develops after nephrectomy, angiotensin I dose—response curves and rat renin clearances were studied in nephrectomized rats and paired sham-nephrectomized control animals under pentobarbitone anaesthesia. 2. Both threshold and slope of the angiotensin I dose—response curves were decreased at 15–27 h after nephrectomy. 3. The ratio of renin clearance (determined during renin infusions) in the nephrectomized rat to that in the paired sham-nephrectomized control animals was 0·49 ± 0·03 (sem), P < 0·001 (n = 12 pairs). 4. Both factors contribute towards the prolongation of the blood pressure increase after intravenously administered renin in the nephrectomized animal.

The Effect of Dietary Sodium Intake on the Blood Pressure and Cardiac Output Responses to Angiotensin II in Unanaesthetized Rats

1977 ◽  
Vol 52 (6) ◽  
pp. 571-576
Author(s):  
Barbara L. Slack ◽  
J. M. Ledingham
Keyword(s):  
Blood Pressure ◽  
Cardiac Output ◽  
Angiotensin Ii ◽  
Dose Response ◽  
Sodium Intake ◽  
Pressor Response ◽  
Peripheral Resistance ◽  
Response Curves ◽  
Low Sodium ◽  
Dose Response Curves

1. Dose—response curves for the pressor activity of angiotensin II have been determined in unanaesthetized rats receiving diets containing 2·5% (w/w) or 0·007% (w/w) sodium and administered in various sequences. 2. Dose—response curves were shifted to the left in rats on a high-, compared with a low-, sodium intake. This response was maintained for 7 days on changing from high to low sodium. 3. There was no difference in the relation between the fall of cardiac output and the rise of blood pressure in any of the experimental groups. 4. Dose—response curves for peripheral resistance showed the same directional change as seen for the pressor response in rats on high- and low-sodium diets. Since depression of cardiac output was proportional to the pressure rise, the absolute change in peripheral resistance was greater than the blood pressure response. The proportional changes were similar. 5. It is concluded that alterations in the pressor response to angiotensin caused by changes in sodium loading are attributable to changes in peripheral resistance and not to changes in the cardiac output response to the acute rise in blood pressure.

The effect of prostaglandin E1 upon the pressor and hormonal response to exogenous angiotensin II in human pregnancy

1987 ◽  
Vol 72 (3) ◽  
pp. 351-357 ◽  
Author(s):  
F. Broughton Pipkin ◽  
R. Morrison ◽  
P. M. S. O'Brien
Keyword(s):  
Blood Pressure ◽  
Dose Response ◽  
Prostaglandin E1 ◽  
Age Groups ◽  
Plasma Aldosterone ◽  
Ang Ii ◽  
Hormonal Response ◽  
Response Curves ◽  
Basal Blood Pressure ◽  
Dose Response Curves

1. The effect of prostaglandin E1 (PGE1) on the pressor and hormonal response to angiotensin (ANG) II has been studied in 22 women in second trimester pregnancy. Three-point dose–response curves were initially determined for all women. Eleven then received an infusion of PGE1 while the remainder received an infusion of normal saline as controls. The dose–response curves to ANG II were re-studied after a period of stabilization. 2. Although assignation to treatment group was random, differences were found in age and basal blood pressure between the control group and those given PGE1. The pressor data from the PGE1 group were thus split by age for analysis. 3. The administration of ANG II alone was associated with significant (P<0.001 at all doses) pressor effects without accompanying bradycardia. Plasma renin concentration (PRC) was suppressed (P<0.001). Plasma aldosterone concentration rose (P<0.001), the magnitude of the rise being directly associated with the plasma ANG II concentrations achieved (P<0.05). 4. The infusion of PGE, had no significant effect on basal blood pressure, but evoked a sustained tachycardia in both age groups (P<0.001). Basal hormone concentrations were unchanged. 5. The pressor response to ANG II was blunted in the presence of PGE1, in both age groups, the overall effect being greatest when the initial response had been large (P<0.05). Measured plasma concentrations of ANG II were lower under these circumstances (P<0.02). PRC fell (P<0.05 for both groups) and plasma aldosterone concentrations rose (P<0.005 for the treated and P<0.001 for the control groups), but the magnitude of these changes did not differ significantly in the two groups. 6. These data support the hypothesis of a for the vasodilator prostaglandins in minimizing the potential pressor effects of the raised ANG II concentrations seen in pregnancy.

Pressor responsiveness to angiotensin in soy-fed spontaneously hypertensive rats

2002 ◽  
Vol 80 (12) ◽  
pp. 1180-1186 ◽  
Author(s):  
Douglas S Martin ◽  
J L Williams ◽  
Nikolai P Breitkopf ◽  
Kathleen M Eyster
Keyword(s):  
Angiotensin Ii ◽  
Dose Response ◽  
Spontaneously Hypertensive Rats ◽  
Antihypertensive Effect ◽  
Ace Inhibition ◽  
Hypertensive Rats ◽  
Angiotensin I ◽  
Response Curves ◽  
Spontaneously Hypertensive ◽  
Dose Response Curves

Dietary soy may attenuate the development of arterial hypertension. In addition, some soy-containing foods exhibit angiotensin-converting enzyme (ACE) inhibitory properties. Accordingly, we tested the hypothesis that ACE inhibition contributes to the antihypertensive effect of dietary soy. Mean arterial blood pressure (MAP) was recorded from conscious spontaneously hypertensive rats (SHR) at least 24 h after the implantation of catheters. Cumulative dose–response curves to intravenous angiotensin I (AI) (5–100 ng·kg–1·min–1) and angiotensin II (AII) (1–20 ng·kg–1·min–1) were constructed for male, sham-operated female, and ovariectomized female (OVX) SHR that were maintained on either casein or soy diets. The soy diet was associated with a significant reduction in baseline MAP in the OVX SHR (~20 mmHg, 1 mmHg = 133.322 Pa). AI and AII infusions caused graded increases in MAP in all groups. However, there was no significant attenuation of the pressor responses to AI in the soy-fed SHR. Conversely, we observed a significant rightward displacement of the AII dose–response curves in the soy-fed sham-operated and OVX SHR. We conclude that ACE inhibition does not account for the antihypertensive effect of dietary soy in mature SHR.Key words: dietary soy, hypertension, SHR, angiotensin I, angiotensin II.

The Pressor Response to Intravenously Infused Angiotensin II: Correlation with Plasma Renin Activity

1974 ◽  
Vol 46 (2) ◽  
pp. 149-161 ◽  
Author(s):  
J. Deheneffe ◽  
A. Bernard
Keyword(s):  
Angiotensin Ii ◽  
Plasma Renin Activity ◽  
Dose Response ◽  
Pressor Response ◽  
Plasma Renin ◽  
Renin Activity ◽  
Response Curves ◽  
Basal Plasma ◽  
Dose Response Curves ◽  
The Individual

1. When angiotensin II was infused into forty unselected subjects a linear relationship was found between the increment of diastolic blood pressure and the logarithm of the rate of infusion of angiotensin II. 2. The slope of this line was very reproducible on repeated determinations in the same subject. 3. When the correlations between pre-infusion plasma renin activity and various functions derived from dose—response curves were determined, it was observed that: (i) the significance of the correlation became progressively stronger when increasing thresholds of the pressor response to angiotensin II were considered; (ii) the best correlation was achieved when the slopes of the individual dose—response curves were plotted against the logarithm of corresponding plasma renin activities. 4. These results suggest that the slope of the pressor dose—response curve is the most reliable index of responsiveness to intravenously infused angiotensin II and that it may provide a satisfactory guide to the basal plasma renin activity.

Autonomic nervous system and adaptation to cold in man

1975 ◽  
Vol 39 (2) ◽  
pp. 181-186 ◽  
Author(s):  
J. LeBlanc ◽  
S. Dulac ◽  
J. Cote ◽  
B. Girard
Keyword(s):  
Blood Pressure ◽  
Pressor Response ◽  
Cold Pressor ◽  
Pressure Increase ◽  
Quebec City ◽  
Sympathetic Response ◽  
Blood Pressure Increase ◽  
Cold Face ◽  
Cold Face Test ◽  
Made In

The responses to cold hand test (blood pressure increase and tachycardia) and to a cold face test (blood pressure increase and bradycardia) were used to study the role of the autonomic nevrous system in cold adaptation in humans. The Eskimos (men, women, children) were shown to have a very weak sympathetic response to cold but the vagal response (bradycardia) was identical to that of white people. A group of mailmen from Quebec city living outdoors approximately 30 h/wk throughout the year was also studied. A significant decline in the cold pressor response and an enhanced bradycardia (cold face test) were observed at the end of the winter. Similarly the fall in skin temperature of the cheek was not as pronounced when the measurements were made in May compared to those made in October. A group of soldiers was also studied before and after an Arctic expedition. It was found that the bradycardia of the cold face test was also more pronounced after sojourning in the cold. These results indicate that repeated exposures to severe cold in men activate some adaptive mechanisms characterized by a diminution of the sympathetic response and a concomitant enhancement of the vagal activation normally observed when the extremities and the face are exposed to cold.

Inhibition of eledoisin by morin on the isolated guinea pig ileum

1968 ◽  
Vol 46 (1) ◽  
pp. 67-69 ◽  
Author(s):  
André L. Gascon
Keyword(s):  
Blood Pressure ◽  
Guinea Pig ◽  
Dose Response ◽  
The Other ◽  
Guinea Pig Ileum ◽  
Response Curves ◽  
Rat Blood ◽  
Other Hand ◽  
Noncompetitive Inhibitor ◽  
Dose Response Curves

The response of the isolated guinea pig ileum to angiotensin, bradykinin, eledoisin, and acetylcholine was studied before and during exposure to morin. Dose–response curves were made for each agonist in the presence of different concentrations of the flavonoid (1 to 8 μg/ml). Under these conditions, the responses of the ileum to eledoisin, angiotensin, and acetylcholine were modified to various degrees depending upon the concentration of morin. With morin 1 μg/ml, the effect of eledoisin was reduced, and the activity of this polypeptide progressively decreased with an increase in the concentration of the inhibitor. On the other hand, the activity of acetylcholine was potentiated while that of bradykinin and angiotensin was unchanged. With higher concentrations of morin (4 and 8 μg/ml), the effect of both angiotensin and acetylcholine was slightly reduced. On the rat blood pressure, morin did not modify the effect of agonists. From these results it is concluded that morin is a specific and noncompetitive inhibitor of eledoisin on the isolated guinea pig ileum.

Dose-response Curves in the Fibrin Plate Assay Fibrinolytic Activity of Proteases

1974 ◽  
Vol 32 (02/03) ◽  
pp. 356-365 ◽  
Author(s):  
F Haverkate ◽  
D. W Traas
Keyword(s):  
Dose Response ◽  
Fibrinolytic Activity ◽  
Enzyme Concentration ◽  
Response Curves ◽  
Agar Gel ◽  
Porcine Tissue ◽  
Plate Assay ◽  
Fibrin Plate ◽  
Different Types ◽  
Dose Response Curves

SummaryIn the fibrin plate assay different types of relationships between the dose of applied proteolytic enzyme and the response have been previously reported. This study was undertaken to determine whether a generally valid relationship might exist.Trypsin, chymotrypsin, papain, the plasminogen activator urokinase and all of the microbial proteases investigated, including brinase gave a linear relationship between the logarithm of the enzyme concentration and the diameter of the circular lysed zone. A similar linearity of dose-response curves has frequently been found by investigators who used enzyme plate assays with substrates different from fibrin incorporated in an agar gel. Consequently, it seems that this linearity of dose-response curves is generally valid for the fibrin plate assay as well as for other enzyme plate bioassays.Both human plasmin and porcine tissue activator of plasminogen showed deviations from linearity of semi-logarithmic dose-response curves in the fibrin plate assay.

BIOASSAY OF THYROID HORMONE USING HYPOTHYROID TADPOLES

1962 ◽  
Vol 41 (1) ◽  
pp. 143-153 ◽  
Author(s):  
U. Henriques
Keyword(s):  
Thyroid Hormone ◽  
Dose Response ◽  
Developmental Rate ◽  
Response Curves ◽  
Sodium Salts ◽  
Dose Response Curves

ABSTRACT A bioassay of thyroid hormone has been developed using Xenopus larvae made hypothyroid by the administration of thiourea. Only tadpoles of uniform developmental rate were used. Thiourea was given just before the metamorphotic climax in concentrations that produced neoteni in an early metamorphotic stage. During maintained thiourea neotoni, 1-thyroxine and 1-triiodothyronine were added as sodium salts to the water for three days and at the end of one week the stage of metamorphosis produced was determined. In this way identical dose-response curves were obtained for the two compounds. No qualitative differences between their effects were noted except that triiodothyronine seemed more toxic than thyroxine in equivalent doses. Triiodothyronine was found to be 7–12 times as active as thyroxine.

Dose Response Curves for Microwave Ablation in the Cardioplegia-Arrested Porcine Heart

2005 ◽  
Vol 8 (4) ◽  
pp. E269-E274 ◽  
Author(s):  
Sydney L. Gaynor ◽  
Gregory D. Byrd ◽  
Michael D. Diodato ◽  
Yosuke Ishii ◽  
Anson M. Lee ◽  
...  
Keyword(s):  
Dose Response ◽  
Microwave Ablation ◽  
Response Curves ◽  
Porcine Heart ◽  
Dose Response Curves

Modeling Nonmonotonic Dose-Response Curves

2001 ◽  
Author(s):  
Quinton J. Nottingham ◽  
Jeffrey B. Birch ◽  
Barry A. Bodt
Keyword(s):  
Dose Response ◽  
Response Curves ◽  
Dose Response Curves
Sign in / Sign up

Export Citation Format

Share Document