scholarly journals Thyrotropin releasing hormone in hypovolemia: a hemodynamic evaluation in the rat

1986 ◽  
Vol 250 (6) ◽  
pp. H1093-H1101 ◽  
Author(s):  
A. L. Siren ◽  
E. Powell ◽  
G. Feuerstein
Keyword(s):  
Renal Artery ◽  
Regional Blood Flow ◽  
Peripheral Resistance ◽  
Resistance Index ◽  
Thyrotropin Releasing Hormone ◽  
Pulsed Doppler ◽  
Conscious Rat ◽  
Releasing Hormone ◽  
Total Peripheral Resistance Index ◽  
Hypovolemic Hypotension

In the present study the effects of thyrotropin releasing hormone (TRH) and its stable analogue, CG3703, on cardiac output (thermodilution, Cardiomax) and regional blood flow (BF; directional pulsed Doppler technique) were investigated in hypovolemic hypotension in the rat. In urethan-anesthetized rats TRH (0.5 or 2 mg/kg ia) or CG3703 (0.05 or 0.5 mg/kg ia) reversed the bleeding (27% of the blood volume)-induced decreases in mean arterial pressure (MAP) and cardiac index (CI) and increased the heart rate (HR) and total peripheral resistance index (TPRI) in a dose-related manner. In the conscious rat exposed to a 45% hemorrhage, CG3703 (0.5 mg/kg ia) significantly raised MAP, HR, and TPRI with maximum changes of +67 +/- 6 (SE) mmHg, +123 +/- 30 beats/min, and +101 +/- 2%, respectively, CG3703 (0.5 mg/kg ia) also further enhanced the hemorrhage-induced reduction of hindquarter, mesenteric, and renal BF. The changes in BF in saline-treated vs. CG3703-treated rats 2 h after the bleeding were -32 +/- 6 vs. -55 +/- 6% (P less than 0.001) in hindquarter, -9 +/- 8 vs. -61 +/- 11% (P less than 0.001) in mesenteric, and -2 +/- 9 vs. -33 +/- 9% (P less than 0.01) in the renal artery; the changes in vascular resistance +30 +/- 7 vs. +309 +/- 167% (P less than 0.001) in hindquarter, -4 +/- 8 vs. +349 +/- 244% in the mesenteric, and -10 +/- 9 vs. +80 +/- 10% (P less than 0.01) in the renal artery. The survival rate after the 45% hemorrhage was significantly reduced by both TRH and CG3703.(ABSTRACT TRUNCATED AT 250 WORDS)

Hemodynamics of hemorrhage in the conscious rat and chicken

1986 ◽  
Vol 251 (5) ◽  
pp. R846-R850 ◽  
Author(s):  
J. M. Ploucha ◽  
G. D. Fink
Keyword(s):  
Vascular Tone ◽  
Peripheral Resistance ◽  
Fluid Loss ◽  
Pulsed Doppler ◽  
Vascular Response ◽  
Peripheral Vascular ◽  
Conscious Rat ◽  
Vascular Responses ◽  
Anesthetic Agents ◽  
On Line

Hemodynamic responses to hemorrhage in conscious chicks (n = 10, 233 g) and rats (n = 10, 309 g) were compared. The animals were fitted with miniature pulsed Doppler aortic flow probes 2 days (chickens) or 5 days (rats) before catheterization, and the experiment began 1 (chickens) or 2 (rats) days later. Mean arterial pressure (MAP) and cardiac output (CO) were recorded continuously and simultaneously digitized to compute total peripheral resistance (TPR). MAP, CO, and TPR values were graphed on-line by a microcomputer and stored for later analysis. A 4-ml hemorrhage reduced MAP and CO by 25 and 43% in the rat, and 15 and 4% in the chickens, respectively. The fall in CO in the rat was due to reduction of stroke volume (SV) unlike the birds where SV was well maintained. TPR was elevated 65% in the rats and fell 13% in the chickens. The minimal fall in CO and SV in these conscious birds suggests that anesthetic agents used previously (i.e., urethane, paraldehyde, phenobarbital, and pentobarbital sodium) suppressed cardiac function. However, they do not account for the lack of a peripheral vascular response during hemorrhage. The chicken apparently maintains MAP by a volume regulating mechanism operating independently of peripheral vascular tone inasmuch as circulating fluid volume restitution is rapid and occurs without vasoconstriction. The rat maintains MAP through reflex cardiac and peripheral vascular responses which eventually may contribute to transvascular fluid loss and the ultimate collapse after prolonged hemorrhagic hypotension.

scholarly journals Regional blood flow measurement with pulsed Doppler flowmeter in conscious rat

1981 ◽  
Vol 241 (2) ◽  
pp. H273-H278 ◽  
Author(s):  
J. R. Haywood ◽  
R. A. Shaffer ◽  
C. Fastenow ◽  
G. D. Fink ◽  
M. J. Brody
Keyword(s):  
Blood Flow ◽  
Vascular Resistance ◽  
Regional Blood Flow ◽  
Pulsed Doppler ◽  
Sound Waves ◽  
Conscious Rat ◽  
Cross Sectional ◽  
Freely Moving ◽  
Flowmeter System ◽  
Doppler Flowmeter

Development of techniques for the continuous measurement of regional blood flow and vascular resistance in intact small animals has been impeded primarily by the bulkiness of flow probes. The availability of an ultrasonic pulsed Doppler flowmeter system enabled us to construct miniaturized probes using 1-mm-diameter piezoelectric crystals that emit a 20-mHz signal and receive the reflected sound waves from passing blood cells. The finished flow probe is approximately 2.5-4 mm long and 2 mm in cross-sectional diameter with lumen diameters appropriate for the rat, ranging from 0.7 to 1.2 mm. This report describes the materials and methods involved in constructing and implanting the probes in rats to monitor renal, mesenteric, and hindquarter blood flow velocity. The accuracy of the pulsed Doppler method in detecting changes in regional blood flow and vascular resistance was established by the demonstration of a highly significant correlation between velocity recorded from the Doppler unit and volume flow recorded simultaneously. These data indicate that the ultrasonic pulsed Doppler flowmeter provides the opportunity to measure changes in regional blood flow and vascular resistance in a conscious freely moving rat.

Hemodynamic monitoring for 24 h in unanesthetized rats

1987 ◽  
Vol 253 (6) ◽  
pp. H1335-H1341 ◽  
Author(s):  
T. L. Smith ◽  
T. G. Coleman ◽  
K. A. Stanek ◽  
W. R. Murphy
Keyword(s):  
Cardiac Output ◽  
Mean Arterial Pressure ◽  
Cardiac Index ◽  
Arterial Pressure ◽  
Stroke Volume ◽  
Diurnal Variation ◽  
Total Peripheral Resistance ◽  
Peripheral Resistance ◽  
Resistance Index ◽  
Total Peripheral Resistance Index

A new technique is described that allows minute-to-minute recordings of cardiac output and arterial pressure in unanesthetized rats for periods of 24 h and longer. Rats were instrumented with electromagnetic flow probes and arterial catheters. An electrical and hydraulic swivel was interposed between the rat and recording apparatus to allow free range of movement. Data were collected and analyzed once each minute by computer. Average 24-h values (mean +/- SD) for the following hemodynamic variables were determined in eight rats [expressed where appropriate as a function of body weight (BW)]: cardiac output (98.1 +/- 14.7 ml/min), cardiac index (29.2 +/- 4.4 ml.min-1.100 g BW-1), mean arterial pressure (92.5 +/- 7.8 mmHg), heart rate (347 +/- 45 beats/min), peak aortic flow (403 +/- 32 ml/min), stroke volume (282 +/- 26 microliters), stroke volume index (84.4 +/- 8.1 microliters/100 g BW), and total peripheral resistance index (3.26 +/- 0.46 mmHg.ml-1.min.100 g BW). These results provide a data base of hemodynamic values for unanesthetized adult, Sprague-Dawley male rats, which has not been previously available. In addition, cardiac index, mean arterial pressure, and total peripheral resistance index demonstrated diurnal variation. Diurnal variation contributed substantially to the overall variance observed within these variables. Hourly variance was also substantial and indicates the use of continuous recordings for short-term experiments.

Effect of 1 Year's Therapy in Essential Hypertension on Systemic Haemodynamics Studied before and after ‘Total’ Autonomic Blockade

1979 ◽  
Vol 57 (s5) ◽  
pp. 11s-13s ◽  
Author(s):  
G. L. Jennings ◽  
P. I. Korner ◽  
M. D. Esler
Keyword(s):  
Essential Hypertension ◽  
Blood Pressure Reduction ◽  
Peripheral Resistance ◽  
Resistance Index ◽  
Antihypertensive Drug Therapy ◽  
Complete Restoration ◽  
Before And After ◽  
Autonomic Blockade ◽  
Normotensive Subjects ◽  
Total Peripheral Resistance Index

1. The haemodynamics of ten patients with essential hypertension were studied before treatment (study 1) and again 1 week after cessation of 1 year's antihypertensive drug therapy (study 2). On each occasion measurements of mean arterial pressure (MAP), cardiac index (CI) and total peripheral resistance index (TPRI) were made before and after ‘total’ pharmacological autonomic blockade (with intravenous propranolol, atropine, phentolamine and clonidine); measurements after ‘total’ autonomic blockade were used to assess the magnitude of the ‘non-autonomic’ component of TPRI, which reflects humoral or structural alterations in the vasculature. 2. The findings before ‘total’ autonomic blockade during study 2 showed that MAP was 18 ± 8 mmHg below the value (135 mmHg) observed during study 1 before treatment, and TPRI had fallen by 33% (P < 0·05) and CI had increased by 23% (P < 0·05). 3. After ‘total’ autonomic blockade the differences in the ‘non-autonomic’ components of the different variables were similar, with ‘non-autonomic’ MAP 14 ± 4 mmHg lower in study 2, TPRI 42% lower (P < 0·005) and CI 28% higher. The value in ‘non-autonomic’ TPRI was now the same as values previously observed in normotensive subjects. 4. We conclude that after 1 year's successful treatment there is complete restoration of ‘non-autonomic’ TPRI as a secondary consequence of the blood pressure reduction.

Enhanced vascular effects of the Ca2+ channel agonist Bay K 8644 in pregnant rabbits

2002 ◽  
Vol 282 (4) ◽  
pp. R952-R959 ◽  
Author(s):  
Rocco Venuto ◽  
Gail Brown ◽  
Marion Schoenl ◽  
György Losonczy
Keyword(s):  
Peripheral Resistance ◽  
Resistance Index ◽  
Bay K 8644 ◽  
Vascular Effects ◽  
Pressor Responses ◽  
Voltage Dependent ◽  
Cardiac Output Index ◽  
Voltage Dependent Calcium Channels ◽  
Fractional Increase ◽  
Total Peripheral Resistance Index

Hemodynamic studies were performed to determine if blunting of vascular pressor responsiveness to vasoconstrictors during pregnancy may be due to impaired L-type voltage-dependent calcium channels (L-VDCC). Bay K 8644 (BAY), an L-VDCC agonist, was infused in pregnant and nonpregnant anesthetized rabbits (10, 20, 40, and 60 μg/kg) and pregnant and nonpregnant conscious, chronically instrumented (conscious) rabbits (10, 25, and 50 μg/kg). BAY infusions resulted in greater elevation of mean arterial pressure in both anesthetized pregnant ( n = 6) vs. nonpregnant ( n = 6) ( P < 0.05) and conscious pregnant ( n = 10) vs. nonpregnant ( n = 10) rabbits ( P < 0.05). Fractional increase over baseline of total peripheral resistance index was greater in pregnant (36 ± 5 to 78 ± 14%) vs. nonpregnant rabbits (14 ± 4 to 52 ± 6%) ( P< 0.02). Cardiac output index did not differ. There was a single high-affinity L-VDCC antagonist aortic binding site with similar number and affinity in pregnant ( n = 7) and nonpregnant ( n = 7) rabbits. In conclusion, stimulation of L-VDCC induces greater pressor responses in pregnant rabbits with heightened peripheral vasoconstriction. This does not appear to be due to a change in L-VDCC receptor parameters.

Peripheral chemoreceptor control of cardiovascular function at rest and during exercise in heart failure patients

2015 ◽  
Vol 118 (7) ◽  
pp. 839-848 ◽  
Author(s):  
Heather Edgell ◽  
M. Sean McMurtry ◽  
Mark J. Haykowsky ◽  
Ian Paterson ◽  
Justin A. Ezekowitz ◽  
...  
Keyword(s):  
Heart Failure ◽  
Heart Rate ◽  
Ejection Fraction ◽  
Total Peripheral Resistance ◽  
Peripheral Resistance ◽  
Resistance Index ◽  
Cardiovascular Control ◽  
Peripheral Chemoreceptor ◽  
Dopamine Infusion ◽  
Total Peripheral Resistance Index

Peripheral chemoreceptor activity/sensitivity is enhanced in chronic heart failure (HF), and sensitivity is linked to greater mortality. This study aimed to determine the role of the peripheral chemoreceptor in cardiovascular control at rest and during exercise in HF patients and controls. Clinically stable HF patients ( n = 11; ejection fraction: 39 ± 5%) and risk-matched controls ( n = 10; ejection fraction: 65 ± 2%) performed randomized trials with or without dopamine infusion (2 μg·min−1·kg−1) at rest and during 40% maximal voluntary contraction handgrip (HG) exercise, and a resting trial of 2 min of inspired 100% oxygen. Both dopamine and hyperoxia were used to inhibit the peripheral chemoreceptor. At rest in HF patients, dopamine decreased ventilation ( P = 0.02), decreased total peripheral resistance index ( P = 0.003), and increased cardiac and stroke indexes ( P ≤ 0.01), yet there was no effect of dopamine on these variables in controls ( P ≥ 0.7). Hyperoxia lowered ventilation in HF ( P = 0.01), but not in controls ( P = 0.9), indicating suppression of the peripheral chemoreceptors in HF. However, no decrease of total peripheral resistance index was observed in HF. As expected, HG increased heart rate, ventilation, and brachial conductance of the nonexercising arm in controls and HF patients. During dopamine infusion, there were no changes in mean arterial pressure, heart rate, or ventilation responses to HG in either group ( P ≥ 0.26); however, brachial conductance increased with dopamine in the control group ( P = 0.004), but decreased in HF ( P = 0.02). Our findings indicate that the peripheral chemoreceptor contributes to cardiovascular control at rest in HF patients and during exercise in risk-matched controls.

scholarly journals Effect of Thyrotropin-Releasing Hormone on Cerebral Blood Flow in Conscious Rat

1989 ◽  
Vol 9 (2) ◽  
pp. 196-203 ◽  
Author(s):  
Yasushi Kondoh ◽  
Shigenori Mizusawa ◽  
Matsutaro Murakami ◽  
Ken Nagata ◽  
Hiroshi Sasaki ◽  
...  
Keyword(s):  
Blood Flow ◽  
Cerebral Blood Flow ◽  
White Matter ◽  
Gray Matter ◽  
Brain Regions ◽  
Thyrotropin Releasing Hormone ◽  
Conscious Rat ◽  
Releasing Hormone ◽  
Conscious Rats ◽  
Prostaglandin Metabolism

The effect of thyrotropin-releasing hormone (TRH) was studied on local CBF (LCBF) in normal conscious rats. LCBF was measured by the autoradiographic [14C]iodoantipyrine method 5 min after TRH (5 mg/kg, i.v.) administration. TRH significantly increased LCBF in 22 of 33 brain regions. This increase of LCBF exceeded 100% of the control values in the cerebral cortices, whereas there was no significant increase in white matter or in some gray matter structures. The increase of CBF following TRH administration was abolished by pretreatment with indomethacin (5 mg/kg, i.v.). The mechanisms underlying the increase of CBF following TRH administration are discussed in relation to prostaglandin metabolism.

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