Compensatory changes in thyroid blood flow are only partially mediated by thyrotropin

1991 ◽  
Vol 260 (4) ◽  
pp. E608-E612
Author(s):  
M. Michalkiewicz ◽  
J. M. Connors ◽  
L. J. Huffman ◽  
Z. Pietrzyk ◽  
G. A. Hedge
Keyword(s):  
Blood Flow ◽  
Hormone Replacement ◽  
Hormone Secretion ◽  
Reference Sample ◽  
Sprague Dawley ◽  
Thyroid Hormone Replacement ◽  
Arterial Blood ◽  
Sprague Dawley Rats ◽  
Tsh Levels

It has been shown that the compensatory growth of the thyroid gland and the compensatory increase in hormone secretion that occur after hemithyroidectomy are preceded by a dramatic increase in thyroid blood flow (BF). These alterations in the thyroid remnant may be due to the concomitant increase in plasma thyrotropin (TSH) concentrations. It has been suggested, however, that the compensatory thyroid growth may also involve a neural reflex. In this study we have investigated the role of TSH in mediating the compensatory alterations in thyroid BF and mass after subtotal thyroidectomy. Male Sprague-Dawley rats were anesthetized with ether for surgical or sham hemithyroidectomy. One-half of the hemithyroidectomized rats (HTX) received no further treatment; in the other one-half of the HTX rats (Clamp), plasma TSH levels were maintained at levels comparable with those in sham-operated animals by initiating constant thyroid hormone replacement beginning at the time of hemithyroidectomy. Plasma samples for TSH, 3,5,3'-triiodothyronine, and thyroxine radioimmunoassays were obtained 2, 7, 14, and 21 days after surgery. Thyroid BF was determined at 1, 2, and 3 wk after surgery by the reference sample version of the radioactive microsphere technique (141Ce, 15 microns diameter). Plasma TSH levels and thyroid lobe weight were significantly elevated in HTX rats but not in Clamp rats. Thyroid BF was markedly increased in HTX rats. Thyroid BF was also significantly increased in Clamp rats despite the suppression of the rise in plasma TSH concentration, but this increase was less than that in HTX rats. Neither hemithyroidectomy nor Clamp treatments had any effect on arterial blood pressure or BF to other tissues (e.g., kidney).(ABSTRACT TRUNCATED AT 250 WORDS)

Effects of NO synthase inhibition on the muscular blood flow response to treadmill exercise in rats

1994 ◽  
Vol 77 (3) ◽  
pp. 1288-1293 ◽  
Author(s):  
T. Hirai ◽  
M. D. Visneski ◽  
K. J. Kearns ◽  
R. Zelis ◽  
T. I. Musch
Keyword(s):  
Blood Flow ◽  
Treadmill Exercise ◽  
No Synthase ◽  
Sprague Dawley ◽  
Flow Response ◽  
Arterial Blood ◽  
Sprague Dawley Rats ◽  
Before And After ◽  
Fast Twitch

The functional role of nitric oxide (NO) release in regulating blood flow (BF) to exercising skeletal muscle was studied in conscious male Sprague-Dawley rats (603 +/- 28 g; n = 6). In this study, BF was measured using radiolabeled microspheres during treadmill exercise (10% grade, 20 m/min) before and after NO synthase (NOS) inhibition with NG-nitro-L-arginine methyl ester (30 mg/kg ia). After NOS inhibition, mean arterial blood pressure increased from resting baseline values and the duration of vasodilator responses to acetylcholine (ACh) injections (3.0 and 10.0 micrograms/kg ia) was diminished (P < 0.05), demonstrating reduced NOS function. During exercise, BF to the kidneys and organs of the gut was reduced after NOS inhibition. In addition, BF was reduced in 16 of the 28 individual hindquarter muscles or muscle parts. Moreover these reductions in BF were linearly correlated with the estimated sum of the percentage of fast-twitch oxidative glycolytic (FOG) and slow-twitch oxidative (SO) types of fibers found in each muscle [delta BF = -1.1 (%SO + %FOG) + 16.4; r = 0.88, P < 0.001]. These results suggest that NO-mediated vasodilation contributes to the BF responses within and among the muscles of the rat's hindquarters during exercise.

Parathyroid Hormone- and Deoxycorticosterone Acetate-Induced Hypertension in the Rat

1980 ◽  
Vol 58 (5) ◽  
pp. 365-371 ◽  
Author(s):  
A. Berthelot ◽  
A. Gairard
Keyword(s):  
Parathyroid Hormone ◽  
Hormone Secretion ◽  
Sprague Dawley ◽  
Physiological Concentration ◽  
Deoxycorticosterone Acetate ◽  
Calcium Diet ◽  
Arterial Blood ◽  
Sprague Dawley Rats ◽  
High Calcium ◽  
High Calcium Diet

1. Hypertension induced by treatment with deoxycorticosterone acetate and sodium chloride was studied in male Sprague-Dawley rats and related to parathyroid hormone secretion. 2. Lack of parathyroid hormone (due to parathyroidectomy) or decreased parathormone secretion (due to a high-calcium diet) partially inhibited the development of arterial hypertension. 3. In contrast, in thyroparathyroidectomized rats supplemented with thyroxine, the administration of parathyroid hormone rapidly elevated arterial blood pressure. 4. Maintaining a physiological concentration of serum calcium in the absence of parathyroid hormone (by feeding a high-calcium diet to parathyroidectomized rats) was not sufficient to establish mineralocorticoid hypertension. 5. These results show that parathyroid hormone is necessary for the complete development of mineralocorticoid hypertension.

Acute cyclosporine-induced renal vasoconstriction: lack of effect of theophylline

1990 ◽  
Vol 258 (1) ◽  
pp. F41-F45
Author(s):  
P. C. Churchill ◽  
N. F. Rossi ◽  
M. C. Churchill ◽  
A. K. Bidani ◽  
F. D. McDonald
Keyword(s):  
Renal Plasma Flow ◽  
Left Kidney ◽  
Chronic Administration ◽  
Sprague Dawley ◽  
Renal Vasoconstriction ◽  
Adenosine Receptor Antagonist ◽  
Arterial Blood ◽  
Sprague Dawley Rats ◽  
Group 1

Both acute and chronic administration of cyclosporine A (CSA) lead to renal vasoconstriction, but the mechanism is not fully understood. The present studies were designed to explore the possible role of adenosine in acute CSA-induced renal vasoconstriction in rats. Six groups of anesthetized Sprague-Dawley rats were studied using standard clearance techniques: group 1 rats were controls; groups 2, 4, and 6 received CSA intravenously at 20, 30, and 40 mg.h-1.kg body wt-1, respectively; groups 3 and 5 were identical to groups 2 and 4 except that a priming injection of theophylline was given (56 mumol/kg body wt) and theophylline was included in the intravenous infusate (0.56 mumol.min-1.kg body wt-1). CSA produced acute and concentration-dependent reductions in renal plasma flow (left kidney) and in the clearances of p-aminohippuric acid and inulin (both kidneys). Except in group 6, these changes were observed in the absence of a decrease in arterial blood pressure, demonstrating that CSA produced an acute and concentration-dependent increase in renovascular resistance. Theophylline not only failed to block CSA-induced renal vasoconstriction, if anything, it potentiated it. Because theophylline is an adenosine receptor antagonist, these findings contradict the hypothesis that adenosine mediates acute CSA-induced renal vasoconstriction.

Role of glucagon in splanchnic hyperemia of chronic portal hypertension

1986 ◽  
Vol 251 (5) ◽  
pp. G674-G677 ◽  
Author(s):  
J. N. Benoit ◽  
B. Zimmerman ◽  
A. J. Premen ◽  
V. L. Go ◽  
D. N. Granger
Keyword(s):  
Blood Flow ◽  
Portal Hypertension ◽  
Venous Blood ◽  
Reference Sample ◽  
Venous Hypertension ◽  
Arterial Blood Flow ◽  
Venous Blood Flow ◽  
Portal Vein Stenosis ◽  
Arterial Blood

The role of glucagon as a blood-borne mediator of the hyperdynamic circulation associated with chronic portal venous hypertension was assessed in the rat portal vein stenosis model. Selective removal of pancreatic glucagon from the circulation was achieved by intravenous infusion of a highly specific glucagon antiserum. Blood flow to splanchnic organs, kidneys, and testicles was measured with radioactive microspheres, and the reference-sample method. Glucagon antiserum had no effect on blood flow in the gastrointestinal tract of sham-operated (control) rats. However, the antiserum produced a significant reduction in hepatic arterial blood flow in the control rats, suggesting that glucagon contributes significantly to the basal tone of hepatic arterioles. In portal hypertensive rats glucagon antiserum significantly reduced blood flow to the stomach (22%), duodenum (25%), jejunum (24%), ileum (26%), cecum (27%), and colon (26%). Portal venous blood flow was reduced by approximately 30%. The results of this study support the hypothesis that glucagon mediates a portion of the splanchnic hyperemia associated with chronic portal hypertension.

Salutary effects of androstenediol on cardiac function and splanchnic perfusion after trauma-hemorrhage

2004 ◽  
Vol 287 (2) ◽  
pp. R386-R390 ◽  
Author(s):  
Tomoharu Shimizu ◽  
Mashkoor A. Choudhry ◽  
Laszlo Szalay ◽  
Loring W. Rue ◽  
Kirby I. Bland ◽  
...  
Keyword(s):  
Blood Flow ◽  
Cardiac Function ◽  
Cytokine Production ◽  
Cardiovascular Function ◽  
Organ Blood Flow ◽  
Sprague Dawley ◽  
Splanchnic Perfusion ◽  
Arterial Blood ◽  
Sprague Dawley Rats ◽  
Circulating Levels

Recent studies have shown that dehydroepiandrosterone (DHEA) administration after trauma-hemorrhage (T-H) improves cardiovascular function and decreases cytokine production in male animals. Although androstenediol, one of the metabolites of DHEA, is reported to have estrogen-like activity, it remains unknown whether androstenediol per se has any salutary effects on cytokines and cardiovascular function after T-H. To examine this effect, male Sprague-Dawley rats underwent laparotomy and were bled to and maintained at a mean arterial blood pressure of 35–40 mmHg for ∼90 min. The animals were resuscitated with four times the volume of maximal bleedout volume in the form of Ringer lactate. Androstenediol (1 mg/kg body wt iv) or vehicle was administered at the end of resuscitation. Twenty-four hours after resuscitation, cardiac function and organ blood flow were measured by using 85Sr-microspheres. Circulating levels of nitrate/nitrite and IL-6 were also determined. Cardiovascular function and organ blood flow were significantly depressed after T-H. However, these parameters were restored by androstenediol treatment. The elevated plasma IL-6 levels after T-H were also lowered by androstenediol treatment. In contrast, plasma levels of nitrate/nitrite were the highest in the androstenediol-treated T-H animals. Because androstenediol administration after T-H decreases cytokine production and improves cardiovascular function, this agent appears to be a novel and useful adjunct for restoring the depressed cardiovascular function and for cytokine production in males after adverse circulatory conditions.

Nitric Oxide in the Gracile Nucleus Mediates Depressor Response to Acupuncture (ST36)

2003 ◽  
Vol 90 (2) ◽  
pp. 780-785 ◽  
Author(s):  
Shuang Chen ◽  
Sheng-Xing Ma
Keyword(s):  
Nitric Oxide ◽  
Cardiovascular Response ◽  
Cardiovascular Responses ◽  
Sprague Dawley ◽  
Arterial Blood ◽  
Gracile Nucleus ◽  
Sprague Dawley Rats ◽  
Antisense Oligos ◽  
Stimulation Of

The purpose of these studies was to determine the role of gracile nucleus and the effects of l-arginine-derived nitric oxide (NO) synthesis in the nucleus on the cardiovascular responses to electroacupuncture (EA) stimulation of “Zusanli” (ST36). Arterial blood pressure and heart rate were monitored during EA stimulation of ST36 following microinjections of agents into gracile nucleus. EA ST36 produced depressor and bradycardiac responses in anesthetized Sprague-Dawley rats. The cardiovascular responses to EA ST36 were blocked by bilateral microinjection of lidocaine into gracile nucleus. Microinjection of l-arginine into gracile nucleus facilitated the hypotensive and bradycardiac responses to EA ST36. The cardiovascular responses to EA ST36 were attenuated by bilateral microinjection of neuronal NO synthase (nNOS) antisense oligos into gracile nucleus. Microinjection of nNOS sense oligos into gracile nucleus did not alter the cardiovascular response to EA ST36. The results demonstrate that a blockade of neuronal conduction in the gracile nucleus inhibits the cardiovascular responses to EA ST36. The hypotensive and bradycardiac responses to EA ST36 are modified by influences of l-arginine-derived NO synthesis in the gracile nucleus. We conclude that NO plays an important role in mediating the cardiovascular responses to EA ST36 through gracile nucleus.

Concurrent increases in regional hematocrit and blood flow in diabetic rats: prevention by sorbinil

1992 ◽  
Vol 263 (3) ◽  
pp. H945-H950 ◽  
Author(s):  
S. P. Sutera ◽  
K. Chang ◽  
J. Marvel ◽  
J. R. Williamson
Keyword(s):  
Skeletal Muscle ◽  
Blood Flow ◽  
Sciatic Nerve ◽  
Diabetic Rats ◽  
Sprague Dawley ◽  
Citrate Buffer ◽  
Ocular Tissues ◽  
Arterial Blood ◽  
Transit Times ◽  
Sprague Dawley Rats

These studies were undertaken to investigate the relationship between regional hemodynamic and hemorheological changes in the microvasculature of diabetic rats. Diabetes was induced in male Sprague-Dawley rats by injection of streptozotocin (55 mg/kg body wt). Control rats were injected with vehicle (sodium citrate buffer). A subgroup of diabetic rats was treated with an aldose reductase inhibitor (sorbinil) added to the diet in an amount to provide a daily dose of approximately 0.2 mmol.kg-1.day-1. Three weeks later all animals were anesthetized with thiobutabarbital sodium (Inactin, 100 mg/kg injected intraperitoneally) for assessment of blood flow (by injection of 15 microns microspheres) and regional hematocrit (determined by isotope-dilution techniques using 51Cr-labeled red blood cells and 125I-labeled bovine serum albumin) in selected tissues. The hematocrit in arterial blood samples was identical (approximately 46%) in controls and in diabetics. Regional hematocrits were much lower than arterial hematocrits in control rats and ranged from approximately 20% in ocular tissues, sciatic nerve, diaphragm, and skin to approximately 30% in brain, skeletal muscle, heart, and fat. Hematocrits of diabetic rats were markedly increased in ocular tissues, sciatic nerve, and skin but not in brain, heart, or skeletal muscle. These increases in regional hematocrit were associated with increases in blood flow and were largely prevented by sorbinil. Diabetes induced significant decreases in the mean transit times for whole blood and erythrocytes in all tissues examined except brain, retina, and skin.(ABSTRACT TRUNCATED AT 250 WORDS)

Decreases in organ blood flows associated with increases in sublingual P CO 2 during hemorrhagic shock

1998 ◽  
Vol 85 (6) ◽  
pp. 2360-2364 ◽  
Author(s):  
Xiaohua Jin ◽  
Max Harry Weil ◽  
Shijie Sun ◽  
Wanchun Tang ◽  
Joe Bisera ◽  
...  
Keyword(s):  
Blood Flow ◽  
Hemorrhagic Shock ◽  
Esophageal Wall ◽  
Sprague Dawley ◽  
Shed Blood ◽  
Blood Flows ◽  
Arterial Blood ◽  
Sprague Dawley Rats ◽  
Arterial Blood Lactate ◽  
Highly Correlated

Earlier studies demonstrated that not only the stomach but also the esophageal wall served as an appropriate site for estimating the severity of circulatory shock by using tonometric methods. We then conceived of the option of sublingual tonometry. In the present study, we tested the hypothesis that the changes in sublingual [Formula: see text] serve as indicators of decreases in blood flow to sublingual and visceral tissue. In Sprague-Dawley rats, sublingual[Formula: see text] increased from 50 to 127 Torr and arterial blood lactate increased from 0.9 to 11.2 mmol/l during bleeding. Sublingual blood flow simultaneously decreased to ∼32% of preshock values. After reinfusion of shed blood, organ blood flows and sublingual [Formula: see text] were promptly restored to near-baseline values. There were corresponding decreases in blood flows in the tongue, stomach, jejunum, colon, and kidneys during hemorrhagic shock. Increases in sublingual[Formula: see text] were highly correlated with decreases in sublingual blood flow ( r= 0.80), tongue blood flow ( r = 0.81), gastric blood flow ( r = 0.74), jejunal blood flow ( r = 0.65), colon blood flow ( r = 0.80), and renal blood flow ( r = 0.75). Unbled control animals demonstrated no significant changes. Therefore, we anticipate that sublingual tonometry will provide a useful, noninvasive alternative for monitoring visceral [Formula: see text].

L-NNA decreases cortical hyperemia and brain cGMP levels following CO2 inhalation in Sprague-Dawley rats

1994 ◽  
Vol 267 (2) ◽  
pp. H837-H843 ◽  
Author(s):  
K. Irikura ◽  
K. I. Maynard ◽  
W. S. Lee ◽  
M. A. Moskowitz
Keyword(s):  
Blood Flow ◽  
Vessel Diameter ◽  
Sprague Dawley ◽  
Doppler Flowmetry ◽  
Cranial Window ◽  
Sprague Dawley Rats ◽  
Acetylcholine Inhalation ◽  
Flow Changes ◽  
Pial Vessel

The role of nitric oxide (NO) in the response to 5% CO2 inhalation was investigated by measuring 1) regional cerebral blood flow (rCBF) by laser-Doppler flowmetry and pial vessel diameter through a closed cranial window after topical NG-nitro-L-arginine (L-NNA, 1 mM), and 2) the time-dependent changes in brain guanosine 3',5'-cyclic monophosphate (cGMP) levels after L-NNA (10 mg/kg ip). When L-NNA (but not NG-nitro-D-arginine) was applied topically for 30 or 60 min, the response to hypercapnia was significantly attenuated. A correlation was found between inhibition of brain NO synthase (NOS) activity and the rCBF response (r = 0.77; P < 0.01). However, L-NNA applied 15 min before hypercapnia did not attenuate the increase in rCBF but did attenuate the dilation to topical acetylcholine. Inhalation of CO2 (5%) elevated brain cGMP levels by 20–25%, and L-NNA reduced this response. These data from the rat suggest that 1) a product of NOS activity is associated with hypercapnic hyperemia and the attendant increase in brain cGMP levels, and 2) hypercapnic blood flow changes may not be dependent on endothelial NOS activity within pial vessels.

Changes in regional vascular resistance and blood volume after hemorrhage in fed and fasted awake rats

1995 ◽  
Vol 78 (6) ◽  
pp. 2025-2032 ◽  
Author(s):  
D. N. Darlington ◽  
R. O. Jones ◽  
L. Marzella ◽  
D. S. Gann
Keyword(s):  
Blood Flow ◽  
Blood Volume ◽  
Vascular Resistance ◽  
Bronchial Artery ◽  
Peripheral Resistance ◽  
Sprague Dawley ◽  
Arterial Blood ◽  
Sprague Dawley Rats ◽  
Before And After ◽  
Fasted Rats

To determine whether fasting alters the response of blood flow to hemorrhage, blood flow was measured by radiolabeled microspheres before and after a 20 ml.kg-1.3 min-1 hemorrhage in fed and fasted chronically cannulated male Sprague-Dawley rats. Restitution of blood volume, as determined by dilution of hematocrit, was attenuated in fasted rats, although the responses of arterial blood pressure, heart rate, cardiac output, and total peripheral resistance were not significantly different. Fasting only affected resting blood flow in the bronchial artery and fat and had no effect on resting vascular resistance in any organ studied. In both fed and fasted rats, hemorrhage led to a significant fall in blood flow to the stomach, small intestine, cecum, colon, spleen, pancreas, kidney, bronchial artery, thymus, and muscle and a rise in blood flow to the adrenals. However, fasting did not significantly alter the response of flow or vascular resistance to these organs. Fasting did alter the blood flow response to hemorrhage in bone, fat, and the hepatic artery. These results demonstrate that 24 h of fasting does not affect the responses of blood flow and vascular resistance to hemorrhage in most organs, even though restitution of blood volume is attenuated.

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