bluuebunny/crossref_metadata_2025_split huggingface dataset:
PRELIMINARY STUDIES ON INCREASED NALOXONE POTENCY AND ITS RELATIONSHIP TO MORPHINE TOLERANCE AND DEPENDENCE IN MICE
Authors: Wong Chak‐Lam , Wai Man‐Keung , Roberts Michael B. 
Published: June 2007

SUMMARY1. Morphine pretreatment (8 0 mg/kg s.c.) induced no overt tolerance to its antinociceptive effect in mice 4 h later, but enhanced the antagonistic potency of naloxone.2. A molecular sieve morphine pellet implanted for 24 h induced measurable tolerance, but the relative potency of naloxone was not significantly different from that observed after single‐dose morphine pretreatment. The development of tolerance and increased naloxone potency do not, therefore, run parallel.3. Naloxone‐precipitated withdrawal symptoms were observed after single‐dose morphine and after pellet implantation. However, molecular sieve morphine pellet implantation induced a higher degree of dependence as compared with single dose morphine pretreatment.4. These results indicate that the rate of development of increased naloxone potency and of morphine tolerance and dependence do not run parallel. This implies that caution must be exercised in regarding increased naloxone potency as a sensitive indicator of the initiation and development of tolerance and dependence to morphine.
ROLE OF THE AUTONOMIC NERVOUS SYSTEM IN THE ACUTE RESPONSES TO RENAL ARTERY PRESSURE REDUCTION IN CONSCIOUS DOGS
Authors: Anderson W. P. , Casley D. J. 
Published: June 2007

SUMMARY1. Plasma renin and arterial pressure responses to acute renal artery pressure reduction were compared in intact dogs and ‘autonomically‐blocked’ dogs subjected to adrenalectomy, chronic guanethidine treatment and acute vagal block (methscopolamine).2. Following reduction of renal artery pressure plasma renin activity and concentration rose more in the autonomically blocked dogs than in the intact dogs. When renal artery pressure was held at 30 mmHg for 1 h, plasma renin activity rose by 19‐1 ng/ml per h (range 11‐6‐28‐7) in autonomically blocked dogs and 3‐65 ng/ml per h (range 1‐54‐5‐89) in intact dogs. When renal artery pressure was held at 60 mmHg plasma renin activity rose 3‐28 ng/ml per h (range 2‐4‐4‐7) and 1‐90 ng/ml per h (range 1‐30‐3‐56), respectively.3. Arterial blood pressure also rose more in autonomically blocked dogs in accord with the greater rise in plasma renin activity. The relationships between the increases in arterial pressure and plasma renin were closely similar in the two groups.4. We conclude that the relase of renin and increase in arterial blood pressure in response to renal artery stenosis is normally inhibited by arterial baroreflexes.
TISSUE DISTRIBUTION OF ORALLY ADMINISTERED BISMUTH IN THE RAT
Authors: Lee S. P. , Lim T. H. , Pybus J. , Clarke A. C. 
Published: June 2007

SUMMARY1. A colloidal bismuth preparation, tripotassium dicitrato‐bismuthate, was given (172 mg/kg body weight, 6/7 days) to 10 laboratory rats for 14 months. Bismuth was measured by atomic absorption spectrometry in various tissues and the pattern of distribution studied.2. Bismuth was present in kidney, lung, spleen, liver, brain, heart and skeletal muscles, in descending order of abundance. Haematological data, renal and liver function tests were normal in the bismuth‐treated group.3. The data suggested that chronic ingestion of bismuth in large doses in rats results in absorption and binding to tissues. Absorbed bismuth probably crosses the blood‐brain barrier.
DETERMINATION OF CATHETER WALL HEAT TRANSFER IN CARDIAC OUTPUT MEASUREMENT BY THERMODILUTION*
Authors: Kim M. E. , Lin Y. C. 
Published: June 2007

SUMMARY1. A model system of the thermal dilution technique was used to determine in vitro the loss of thermal indicator across different sizes of polyethylene catheters.2. Thermal indicator loss (caloric gain by the indicator fluid or caloric loss by the catheter) per unit length of catheters (H/L) increased as a function of the outer radius (OR) of the catheters. Linear regression analysis gave the following equation: H/L=0‐337OR+0‐073 (r=0‐88, P<0‐05).3. Thermal indicator loss per unit surface area (H/SA) decreased almost linearly with the following regression equation: H/SA =–1‐860 OR+0‐364 (r=0‐97, P<001).4. Thermal indicator loss per unit volume contained in the catheter (H/vol) decreased exponentially according to the following equation: H/vol = 89‐le−25.4(OR) (r=0‐97, P<001).5. This study indicates that there is a measurable loss of thermal indicator during injection corresponding to a loss of between 9 and 16% (for a 11.5 cm length of PE 50 and PE 240) of the required calories for warming the injectate to 37°C. Data is provided for correction of heat loss across the wall of a given length and diameter of polyethylene tubing.
RENIN SECRETION AND RENAL VASCULAR RESISTANCE FOLLOWING PROLONGED ADMINISTRATION OF DESOXYCORTICOSTERONE (DOC) IN RATS DRINKING NORMAL SALINE
Authors: Vandongen R. , Tunney Anne 
Published: June 2007

SUMMARY1. The effect of long‐term administration of desoxycorticosterone (DOC)‐saline on arterial blood pressure, renal vascular resistance and renin secretion rate was studied in the rat.2. Renin secretion rate and peripheral plasma renin activity was markedly reduced in the DOC‐saline treated rats. Renal vascular resistance was comparable to that found in a corresponding control group. Responsiveness to isoprenaline suggested that the β‐adrenoceptor mediating renin release was grossly intact.3. A significant rise in blood pressure occurred in only 50% of the treated animals: However, no differences in weight gain, renal vascular resistance or renin levels were apparent when compared with animals which remained normotensive.4. These findings indicate that suppression of renin secretion during prolonged DOC‐saline administration cannot be directly attributed to changes in arterial pressure, renal vascular resistance or β‐adrenoceptor sensitivity.
HAEMODYNAMICS OF HYPERTENSION IN PREGNANCY ASSESSED BY M‐MODE ECHOCARDIOGRAPHY
Authors: Larkin Hugh , Gallery Eileen D. M. , Hunyor Stephen N. , Gyory Akos Z. , Boyce E. Stewart 
Published: June 2007

SUMMARY1. Echocardiographic haemodynamic and left ventricular parameters were determined in twenty‐one normotensives and thirty‐six hypertensives during the last trimester of pregnancy.2. Equivalent blood pressure control was obtained in hypertensives with bed rest only, oxprenolol or methyldopa, but remained above normotensive levels.3. Cardiac output was elevated in the last trimester of pregnancy in normotensives and hypertensives.4. Left ventricular mass was increased in normal pregnancy, but displayed an exaggerated increase in hypertensives.5. Total peripheral resistance was inappropriately elevated in hypertensive pregnancy, but was normalized in the oxprenolol‐treated group.6. There was no reduction in heart rate or cardiac output in the β‐adrenoreceptor blocker‐treated group. This feature, in combination with lowered peripheral resistance, may contribute to the improvement in foetal outcome observed in maternal hypertension of pregnancy treated with oxprenolol.
ACTH HYPERTENSION MODIFIES THE HAEMODYNAMIC EFFECTS OF PROSTACYCLIN INFUSIONS IN SHEEP
Authors: Mason R. T. , Allen K. J. F. , Coghlan J. P. , Denton D. A. , Fei D. T. , Graham W. F. , Scoggins B. A. , Stewart K. W. 
Published: June 2007

SUMMARY1. The haemodynamic effects of short‐term prostacyclin infusions (0.05‐0 50 /μg/kg per min) were investigated in conscious adult sheep.2. Haemodynamic dose‐response curves to prostacyclin were performed before, during and after production of ACTH‐induced hypertension.3. Prior to ACTH administration prostacyclin produced dose‐dependent reductions in mean arterial pressure, total peripheral resistance and stroke volume and these were accompanied by increases in heart rate and cardiac output.4. After 5 days of ACTH‐induced hypertension prostacyclin produced similar effects on mean arterial pressure to those seen prior to ACTH but the effects on heart rate, cardiac output, stroke volume and total peripheral resistance were markedly increased.5. These studies demonstrate that the responsiveness of the circulation to prostacyclin is altered in ACTH‐induced hypertension.
INHIBITION BY HYDRALAZINE OF THE CONVERSION OF DOPAMINE TO NORADRENALINE IN RAT ATRIA IN VITRO AND IN VIVO
Authors: Songkittiguna P. , Majewski H. , Rand M. J. 
Published: June 2007

SUMMARY1. Hydralazine (10 to 2000 μnol/1) produced a concentration‐dependent inhibition of the conversion of (3H)‐dopamine to (3H)‐noradrenaline in rat isolated atria.2. In rats treated with hydralazine (2 mg/kg, i.p.), there was an inhibition of the conversion of (3H)‐dopamine to (3H)‐noradrenaline in the intact atria in vivo.3. Hydralazine treatment may result in the appearance of dopamine as a significant co‐transmitter in noradrenergic nerves, and this may contribute to the antihypertensive effect of hydralazine.
EFFECT OF ACTH ADMINISTRATION ON THE HAEMODYNAMIC RESPONSE TO ARGININE‐VASOPRESSIN IN SHEEP
Authors: Coghlan John P. , Denton Derek A. , Graham William F. , Humphrey Timothy J. , Mason Rex T. , Schnieder Edward G. , Scoggins Bruce A. , Whitworth Judith A. 
Published: June 2007

SUMMARY1. Blood pressure, heart rate and cardiac output were studied in intact conscious sheep during AVP infusion at 0.1, 0.25, 0.5 and 10 μg/min for 30 minutes to determine whether pressor responsiveness to AVP was altered in ACTH‐induced hypertension.2. Prior to ACTH treatment, AVP produced rises in blood pressure associated with a fall in heart rate and cardiac output.3. During ACTH treatment, pressor responsiveness to AVP and decrease in cardiac output were unchanged, but reflex bradycardia was reduced.4. ACTH‐induced hypertension in sheep is not associated with enhanced pressor responsiveness to AVP.
ACTIVATION OF PLASMA PREKALLIKREIN AND INACTIVE RENIN BY PUFF ADDER VENOM
Authors: Morris Brian J. , Lawrence Christopher H. , Catanzaro Daniel F. 
Published: June 2007

SUMMARYThe activation of inactive renin during incubation of human plasma with puff adder venom at pH 7 4 was found to be a complex process. Gel nitration on Sephacryl S‐200 indicated that the venom contains a major peak of caseinolytic and renin‐activating activity of low molecular weight. This enzyme was a metalloproteinase. During incubation with plasma the metalloproteinase formed a complex with α2‐macroglobulin and retained caseinolytic and renin‐activating activity. Venom metalloproteinase activated prekallikrein, but not plasmin, and plasma kallikrein may account for at least part of the activation of inactive renin observed.
HAEMODYNAMIC CHANGES IN ACTH‐INDUCED HYPERTENSION IN SHEEP
Authors: Graham W. F. , Allen K. J. F. , Coghlan J. P. , Denton D. A. , Humphery T. J. , Scoggins B. A. , Whitworth J. A. 
Published: June 2007

SUMMARY1. ACTH (20 μg/kg per day) produced an elevation in blood pressure associated with an increase in cardiac output in conscious sheep, due in the first 72 h to a rise in heart rate. Stroke volume did not rise until the fourth day of ACTH treatment.2. Calculated total peripheral resistance did not change.3. Intravenous administration of acebutolol prior to and during ACTH administration did not modify the rise in blood pressure, but this was associated with a rise in total peripheral resistance.4. These studies show that while ACTH‐induced hypertension is usually associated with increased cardiac output, rather than total peripheral resistance it still occurs, but is associated with a rise in total peripheral resistance if the rise in cardiac output is prevented by /J‐adrenoreceptor blockade.
TESTOSTERONE‐ANTIBIOTIC EFFECTIVENESS ON STAPHYLOCOCCUS AUREUS INFECTED RATS
Authors: Atef M. , Sokkar S. M. 
Published: June 2007

SUMMARY(1) Male castrated rats (testosterone‐free) inoculated intraperitoneally with Staph, aureus showed severe damage in their internal organs as determined by pathological examination of the killed animals.(2) Penicillin‐G, oxytetracycline and chloramphenicol treatment 24 h after injection markedly decreased the extent of damage.(3) Pretreatment of castrated rats with testosterone propionate for 3 successive days before infection had a protective influence on the internal organs.(4) Testosterone‐injected rats when treated with different antibiotics, showed a clear synergistic action with penicillin‐G and oxytetracycline but not chloramphenicol.
TOBACCO SMOKING AND CORTICAL EVOKED POTENTIALS: AN OPPOSITE EFFECT ON AUDITORY AND VISUAL SYSTEMS
Authors: Friedman Jeannette , Meares Russell 
Published: June 2007

SUMMARY1. Auditory and visual evoked potentials produced by five intensities of tones and light flashes were recorded in twelve young men who were habitual smokers.2. The subjects attended the laboratory on four occasions. Two recordings were made on each of the last three of these visits. They were made (i) before and after smoking, (ii) without smoking, (iii) before and after smoking after 12 h abstinence from smoking.3. Smoking was associated with increases in the amplitudes of the components V‐VI, VI‐VII in the visual system and a decrease in the amplitude of N2P2 in the auditory system. Abstinence from smoking produced effects in the opposite direction.4. These findings are consistent with the possibility that smoking has different and perhaps opposite effects on the visual and auditory system.5. The findings may be helpful in re‐evaluating some of the apparently conflicting reports on the effects of smoking on perceptual processes.
THE EFFECTS OF CAPTOPRIL (SQ 14,225) ON THE SYSTEMIC AND CORONARY HAEMODYNAMICS OF THE INTACT ANAESTHETIZED DOG
Authors: Maxwell G. M. , Rencis V. , Ness D. 
Published: June 2007

SUMMARY1. The effects of Captopril (SQ14,225), an inhibitor of angiotensin‐converting enzyme, given intravenously in a dose of 0–3 mg/kg was studied in intact anaesthetized dogs.2. The drug caused a decrease in systemic and pulmonary arterial mean pressures, an increase in cardiac output, and hence a decrease in calculated systemic and pulmonary vascular resistances. A sustained tachycardia also occurred.3. A minor, transient increase in coronary sinus flow was recorded, with a sustained decrease in calculated coronary vascular resistance.4. No change was found in cardiac oxygen metabolism nor in calculated cardiac efficiency.5. The plasma renin values increased in the control animals and those given the drug.
EFFECT OF ADRENOCORTICAL STEROIDS AND THEIR STRUCTURAL ANALOGUES ON BLOOD PRESSURE IN SHEEP
Authors: Whitworth Judith A. , Allen Kingsley J. F. , Coghlan John P. , Denton Derek A. , Fan James S. K. , Humphery Timothy J. , McDougall John G. , Scoggins Bruce A. 
Published: June 2007

SUMMARY1. A model of adrenocortical steroid‐induced hypertension based on the effects of ACTH administration has been developed in sheep. The present studies examine the effects of a number of different steroid hormones on blood pressure to investigate their structure‐activity relationships.2. Infusion of the major ovine adrenal steroid hormones (combined steroid infusion of Cortisol, corticosterone, 11‐deoxycortisol, aldosterone, deoxycorticosterone) reproduced the metabolic but not the blood pressure effects of ACTH.3. Addition of 17α, 20α‐dihydroxyprogesterone and 17α‐hydroxyprogester‐one, at rates appropriate for conditions of ACTH stimulation, to the combined steroid infusion reproduced both the blood pressure and metabolic effects of ACTH.4. 17α, 20β‐Dihydroxyprogesterone, 20β‐dihydroxy‐11‐deoxycortisol and 20β‐hydroxycortisol all had additional hypertensive activity when given with combined steroid infusion, but 16α‐hydroxyprogesterone, 11β, 17α‐dihydroxy‐progesterone, 20a‐hydroxyprogesterone and 20α‐hydroxyprogesterone did not.5. These studies support the concept of a new class of steroid hormone action in blood pressure regulation.
SELECTIVE DEVELOPMENT OF TOLERANCE TO β‐ADRENOCEPTOR AGONISTS IN SKELETAL MUSCLE AS COMPARED WITH AIRWAY SMOOTH MUSCLE FROM THE GUINEA‐PIG
Authors: Holmberg E. , Jeppsson A.‐B. , Waldeck B. 
Published: June 2007

SUMMARY1. Guinea‐pigs were fed with a diet containing terbutaline or placebo for 4–5 days. The trachea, soleus muscle and the extensor digitorum longus (EDL) from these animals were prepared for recording of isometric contractions in vitro.2. After treatment with terbutaline in vivo, the response of the pilocarpine‐contracted trachea to terbutaline and isoprenaline was slightly suppressed with no change in maximum relaxation.3. After treatment with terbutaline in vivo the maximum depression of the incomplete tetanic contractions of the soleus muscle brought about by terbutaline or isoprenaline was diminished by about 70%. The response of the EDL was also attenuated after previous treatment with terbutaline in vivo.4. These data indicate a selective development of tolerance to the effects of β‐adrenoceptor agonists in skeletal muscle as compared with tracheal smooth muscle.5. The present results provide an experimental analogue to the clinical observation that patients being treated with β‐adrenoceptor agonists become tolerant to the tremorogenic rather than to the bronchodilating effect.
BARORECEPTOR REFLEX IN THE RAT AFTER CONVERTING ENZYME INHIBITION OR ANGIOTENSIN RECEPTOR BLOCKADE
Authors: Coleman Thomas G. , Salgado Maria Cristina O. , Bengis Roy G. , Davis Milton H. , Dent Ann C. 
Published: June 2007

SUMMARY1. One component of baroreflex responsiveness was quantitated in conscious rats using the heart rate response to a pressor injection of phenylephrine.2. Endogenous angiotensin and its effectiveness were manipulated by sodium deprivation, converting enzyme inhibition and infusion of an angiotensin analogue. None of these manoeuvres changed the observed reflex responsiveness.3. We conclude that endogenous angiotensin has no influence on the component of baroreceptor function that is described by the slope of the arterial pressure‐heart rate relationship.
TOLERANCE TO THE EFFECTS OF Δ1‐TETRAHYDROCANNABINOL ON THE PRESSOR RESPONSES TO NORADRENALINE IN RATS
Authors: Li D. M. F. 
Published: June 2007

SUMMARYl. The depressor response, but not the cardiac slowing response, to the acute intravenous administration of Δ1‐THC (1 mg/kg) was significantly reduced in urethane anaesthetized rats, which had been treated with daily injections of Δ1‐THC (2 mg/kg, i.p.) for 10 days (P<0.01).2. No significant differences in either the depressor or the negative chronotropic effects of an acute intravenous injection of Δ1‐THC (1 mg/kg) were observed in anaesthetized rats which had been treated with PVP (8 mg/kg per day, i.p.) for 10 days.3. The depressor and cardiac slowing responses to an acute intravenous dose of Δ1‐THC (1 mg/kg) were not significantly different between Δ1‐THC‐ and PVP‐treated animals which had been pithed.4. The potentiating effects of Δ1‐THC on the pressor responses to intravenously administered noradrenaline were significantly reduced (P<0.001) in urethane anaesthetized rats which had been treated with Δ1‐THC, but not in anaesthetized PVP‐treated animals.5. Tolerance to the potentiating effect of Δ1‐THC on the responses to noradrenaline has also been demonstrated in anaesthetized Δ1‐THC‐treated rats, but not in pithed Δ1‐THC treated ones.6. It is concluded that the development of tolerance to the depressor action of Δ1‐THC, and its potentiating effect on the noradrenaline pressor responses requires the presence of an intact central nervous system.
ANGIOTENSIN AND THE CARDIAC BAROREFLEX RESPONSE TO PHENYLEPHRINE
Authors: Lee W. B. , Lumbers E. R. 
Published: June 2007

SUMMARY1. In adult conscious sheep the pressor actions of infused angiotensin II were prevented by the concomitant intravenous infusions of sodium nitroprusside. The effect of such intravenous infusions of angiotensin II on the cardiac baroreflex response to transient rises in arterial pressure caused by intravenous phenylephrine was studied.2. Intravenous infusion of angiotensin II caused a reduction in pulse interval in the absence of any change in arterial pressure. It also caused a reduction in baroreflex sensitivity measured by determining the relation between pulse interval and systolic pressure during the rise in pressure caused by injection of phenylephrine.3. After administration of the converting enzyme inhibitor (captopril) the mean baroreflex sensitivity of 3 of 4 pregnant ewes increased.4. It is concluded that high levels of angiotensin II can modify the cardiac baroreceptor reflex response so that the heart rate is inappropriately high for a given systolic pressure and that it reduces the sensitivity of the cardiac baroreflex response to transient changes in arterial pressure.
CIRCULATING HYPOTENSIVE FACTOR IN PREGNANT SPONTANEOUSLY HYPERTENSIVE RATS
Authors: Kubota T. , Yamada T. 
Published: June 2007

SUMMARY1. Blood pressure decreased significantly at a late stage of pregnancy in spontaneously hypertensive rats (SHRs) but this reduction tended to disappear shortly after delivery. Since acute and chronic administration of progesterone, prolactin and estrone failed to reduce blood pressure, these hormones were not responsible for a fall of blood pressure at a late stage of pregnancy in SHRs. Exogenous administration of prostaglandin E2 (PGE2) significantly reduced blood pressure, but endogenous prostaglandin E1 (PGE1), PGE2 and prostaglandin F2α(PGF2α) in plasma did not increase at a late stage of pregnancy.2. Plasma from pregnant SHRs produced a significant reduction of blood pressure in male and female SHRs, but the plasma from male and non‐pregnant female SHRs failed to reduce blood pressure. Plasmas from pregnant SHRs were less effective in reducing blood pressure when tested in Wistar Kyoto rats (WKYs).3. It is concluded that a hypotensive factor is circulating at a late stage of pregnancy in SHRs.
THE EFFECT OF RENAL DENERVATION ON ACTH‐INDUCED HYPERTENSION IN SHEEP
Authors: Whitworth Judith A. , Denton D. A. , Graham W. F. , Humphery T. J. , Scoggins B. A. , Coghlan J. P. 
Published: June 2007

SUMMARY1. The effect of renal denervation on ACTH‐induced hypertension in sheep has been examined.2. Both intact and renally denervated sheep showed similar rises in blood pressure following ACTH treatment.3. Following renal denervation, the initial urinary sodium retention and ACTH‐withdrawal natriuresis typical of ACTH administration in intact sheep were absent, and the fall in blood pressure was delayed.
LACK OF PROLONGED EFFECT OF ANTIDIURETIC HORMONE ON THE RENIN‐ALDOSTERONE SYSTEM IN THE DOG
Authors: Young David B. , McCaa Robert E. 
Published: June 2007

SUMMARY1. The effects of maximally antidiuretic, subpressor antidiuretic hormone (ADH) administration on the renin‐aldosterone system were studied in dogs during 4 days of continuous intravenous infusion of ADH at a rate of 0.067 mU/kg per min. Water intake was limited to 700 ml/day to avoid changes in fluid volume status.2. At the conclusion of the four‐day study, plasma sodium concentration had fallen from 140.3 ± 0.8 to 137.2 ± 2.0 mmol/l, plasma potassium concentration, 22Na space, and mean arterial pressure remained within the control ranges.3. Neither plasma renin activity nor plasma aldosterone concentration showed any tendency to change in response to the ADH infusion.4. The results indicate that physiologic levels of ADH have no prolonged, direct effect on the renin‐aldosterone system.