bluuebunny/crossref_metadata_2025_split huggingface dataset:
ANGIOTENSIN CONVERTING ENZYME DURING ACUTE AND CHRONIC ENALAPRIL THERAPY IN ESSENTIAL HYPERTENSION
Authors: Jackson B. , Johnstoa C. I. 
Published: June 2007

SUMMARY1. The acute and chronic effects of enalapril (MK421) were assessed in a double‐blind randomized trial in subjects with essential hypertension.2. In acute studies, twelve subjects received enalapril (10 mg p.o.), following which there was a fall in blood pressure, maximal at 6 h and lasting for 24 h. Serum MK422 (enalaprilic acid, the bioactive form of enalapril) and serum angiotensin converting enzyme (ACE) inhibition had a similar time course with good correlation between drug levels and ACE inhibition (P<0.001, r= 0.98, n= 16) and between ACE inhibition and the hypotensive effect (P<0.001, r= 0.84, n= 16).3. In chronic studies enalapril was titrated from 5 mg to 20 mg twice a day in eleven hypertensive patients to achieve a diastolic blood pressure <90 mmHg. Treatment continued for 3–12 months. Increasing serum MK422 was correlated with reducing serum ACE activity (P<0.001, r= 0.45, n= 104). The fall in blood pressure correlated both with serum MK422 level (P < 0.05, r= 0.37, n= 39) as well as ACE inhibition (P < 0.01, r= 0.45, n= 42).4. The drug level:ACE inhibition curve was shifted to the right during chronic enalapril treatment. ID50 for serum ACE was 32 ng MK422/ml following the single 10 mg dose of MK421 and 70 ng MK422/ml during chronic treatment. Blood pressure falls during acute and chronic treatment were similar over the range of serum MK422 levels achieved.5. The shift in the drug level:ACE inhibition curve suggests induction of ACE during chronic treatment with enalapril in man.
HAEMODYNAMIC AND NEUROENDOCRINE CONSEQUENCES OF STOPPING SMOKING‐A CONTROLLED STUDY
Authors: Puddey I. B. , Vandongen R. , Beilin L. J. , English D. 
Published: June 2007

SUMMARY1. The haemodynamic and neuroendocrine consequences of stopping smoking for a 6 week period were studied in thirty‐three smokers and their matched controls.2. Complete smoking cessation was associated with a significant fall in adrenaline and cortisol levels, consistent with the withdrawal of a nicotine stimulus to adrenomedullary and cortical activity.3. Supine systolic and diastolic blood pressure did not change significantly. However, the response to a cold pressor stimulus was altered with a delay in return of systolic blood pressure to basal values.4. This study has been unable to confirm findings from epidemiological studies of lower blood pressure in smokers. However, the possibility is raised that this phenomenon may be due to modification by smoking of the normal physiological response to stressful stimuli.
LESIONS OF THE VENTROLATERAL MEDULLA IN NORMAL AND VASOPRESSIN‐DEFICIENT (BRATTLEBORO) RATS
Authors: Minson J. B. , Chalmers J. P. 
Published: June 2007

SUMMARY1. The cardiovascular response to electrolytic lesions of the A1 noradrenaline cell group (A1 lesion) were studied in the rat.2. A1 lesions in normal rats cause acute hypertension and bradycardia and elevate plasma arginine‐vasopressin (AVP), as previously described in the rabbit.3. After A1 lesions in vasopressin deficient rats the hypertension is not reduced compared to that seen in normal rats, but the bradycardia is attenuated.4. AVP makes a greater contribution to the bradycardia than to the hypertension after A1 lesions.
PLASMA ALDOSTERONE LEVELS AFTER KCI LOADING IN RATS ADAPTED TO A HIGH POTASSIUM DIET
Authors: Adam William R. , Campbell Duncan J. 
Published: June 2007

SUMMARY1. Plasma levels of aldosterone, corticosterone, potassium and renin activity, and urinary potassium excretion, were measured in control (CK) rats, and in rats adapted to a high potassium diet (HK), before and after an acute intragastric KCl load.2. Prior to the KCl load there was no difference in plasma potassium (K) or plasma aldosterone.3. Following the KCl load, HK rats maintained a lower plasma K, and, except at 30 min after the load, a lower plasma aldosterone than CK rats.4. At a low plasma K there was no difference in plasma aldosterone between CK and HK rats. At a high plasma K (>8 mmol/l) the HK rats had a higher plasma aldosterone for the same plasma K than CK rats.5. The enhanced ability to excrete an acute K load seen in HK rats seems unlikely to be due to higher levels of plasma aldosterone.
A COMPARISON OF THE HAEMODYNAMIC EFFECTS OF DIETARY SODIUM RESTRICTION AND ACUTE SODIUM DEPLETION IN THE CONSCIOUS SHEEP
Authors: Mason R. T. , Coghlan J. P. , Denton D. A. , Fei D. W. T. , Scoggins B. A. , Stewart K. W. , Whitworth J. A. 
Published: June 2007

SUMMARY1. The use of a low Na, low K sorghum grain diet supplemented with intraruminal electrolyte infusions has enabled dietary manipulation of sodium status to be studied in the sheep.2. Dietary sodium restriction reduced urinary sodium excretion within 24 h with maximal retention after 3 days. There were no other substantial metabolic or haemodynamic changes.3. A more severe form of sodium deficiency produced by parotid salivary drainage resulted after only 2 days in a sodium deficit 3–4 times that seen with 14 days of sodium restriction. Extracellular fluid volume and cardiac output decreased. Blood pressure was unchanged but there was an increase in peripheral resistance and plasma renin concentration.
6‐KETO‐PROSTAGLANDIN E1 AND PROSTAGLANDIN E2 STIMULATE ALDOSTERONE PRODUCTION IN BOVINE ADRENAL GLANDS
Authors: Tsunoda S. , Demura R. , Demura H. 
Published: June 2007

SUMMARY1. In order to investigate the effect of prostaglandins on aldosterone synthesis, dispersed bovine adrenal cells were incubated with prostaglandins and the aldosterone concentration was measured by radioimmunoassay.2. The result was that aldosterone production was stimulated by 6‐keto‐prostaglandin E1 and prostaglandin E2.
CIRCULATING LEVELS OF ARGININE VASOPRESSIN BEFORE AND DURING THE INFUSION OF THE HORMONE IN PATIENTS PRESENTING WITH BLEEDING OESOPHAGEAL VARICES
Authors: Jenkins S. A. , Devitt P. , Baxter J. N. , Shields R. 
Published: June 2007

SUMMARY1. Circulating levels of antidiuretic hormone (ADH) were measured in patients presenting with bleeding oesophageal varices before and during treatment with arginine vasopressin.2. There was no significant difference in the circulating levels of ADH before and during treatment with arginine vasopressin in patients in which the hormone successfully controlled haemorrhage and those in which it did not.3. It is concluded that the failure of vasopressin to control variceal haemorrhage in approximately 40% of patients presenting for treatment cannot be attributed to higher circulating levels of the hormone in these subjects.
A DOUBLE‐BLIND CONTROLLED CLINICAL TRIAL OF MASTIC AND PLACEBO IN THE TREATMENT OF DUODENAL ULCER
Authors: Al‐Habbal Mohammad Jamil , Al‐Habbal Zakaria , Huwez Farhad Umer 
Published: June 2007

SUMMARY1. A double‐blind clinical trial was carried out on thirty‐eight patients with symptomatic and endoscopically proven duodenal ulcer to compare the therapeutic responses to mastic (1 g daily, twenty patients) and placebo (lactose, 1 g daily, eighteen patients) given orally over a period of 2 weeks.2. Symptomatic relief was obtained in sixteen (80%) patients on mastic and in nine (50%) patients on placebo, while endoscopically proven healing occurred in fourteen (70%) patients on mastic and four (22%) patients on placebo. The differences between treatments were highly significant (P<0.01). Mastic was well tolerated and did not produce side effects.3. It is concluded that mastic has an ulcer healing effect, but further studies are needed to establish its role in treating peptic ulcer.
EFFECTS OF CA2+ ANTAGONISTS ON CARDIOVASCULAR RESPONSES TO POSTERIOR HYPOTHALAMIC STIMULATION IN THE RAT
Authors: Eferakeya Adego E. , Osunkwo Uche A. 
Published: June 2007

SUMMARY1. The effects of methoxyverapamil or hydralazine on pressor responses to posterior hypothalamic stimulation and injected pressor agents were studied in normotensive male Wistar rats.2. Methoxyverapamil inhibited both phases of pressor response to hypothalamic stimulation and pressor responses to injected noradrenaline or angiotensin II.3. Hydralazine inhibited the secondary phase (due to adrenomedullary catecholamine) and not the primary phase (due to increased sympathetic vasomotor activity) of pressor response to hypothalamic stimulation. However, it inhibited the pressor responses to exogenous noradrenaline or angiotensin II.4. The data indicate that hydralazine is ineffective in inhibiting the pressor response elicited by noradrenaline endogenously released at the sympathetic nerve endings.
DEMONSTRATION OF α‐ADRENOCEPTOR ANTAGONISM BY THE 5HT2 ANTAGONIST, KETANSERIN (R49945), IN SHEEP
Authors: Nelson M. A. , Coghlan J. P. , Denton D. A. , Mills E. H. , Spence C. D. , Whitworth J. A. , Scoggins B. A. 
Published: June 2007

SUMMARY1. Serotonin causes a dose related (0.1–20 μg/kg i.v.) increase in mean arterial blood pressure (MAP) and heart rate in conscious sheep.2. Ketanserin (0.1 mg/kg per h i.v.) causes a decrease in blood pressure, and an increase in heart rate. In the presence of ketanserin, serotonin induced increases in MAP are attenuated, or abolished, but the increases in heart rate are enhanced.3. Ketanserin (10 mg/kg per h i.v.) attenuates or abolishes the increase in blood pressure induced by the α‐adrenoceptor agonist phenylephrine in conscious sheep. When administered in the presence of the α‐adrenoceptor antagonist prazosin, ketanserin (0.1 mg/kg per h i.v.) fails to induce a further hypotensive response.4. These data suggest that in the conscious sheep ketanserin exhibits predominantly α‐adrenoceptor antagonism.
EFFECTS OF DOXAPRAM ON BODY TEMPERATURE OF THE RAT DURING RADIOFREQUENCY IRRADIATION
Authors: Jauchem James R. , Frei Melvin R. , Heinmets Ferdinand 
Published: June 2007

SUMMARY1. Central nervous system stimulants can cause changes in body temperature and changes in susceptibility to high levels of radiofrequency radiation (RFR). In the present study, the effects of the central nervous system stimulant, doxapram, on thermal responses to 2.8 GHz pulsed RFR were examined in anaesthetized rats.2. During intermittent exposure to an average power density of 60 mW/cm2, doxapram significantly increased the time required for temperature to return to the pre‐exposure level when irradiation was discontinued.3. When exposure was continued until lethal temperatures resulted, doxapram administration caused no significant change in survival time when compared to saline controls. Thus, although the drug decreased thermoregulatory efficiency during intermittent exposure to RFR, no change in susceptibility to terminal RFR exposure was observed.
HISTAMINE AND CARBACHOL CONTRACTILE RESPONSES IN PROXIMAL AND DISTAL AIRWAYS OF THE RABBIT
Authors: Armour C. L. , Black J. L. , Berend N. 
Published: June 2007

SUMMARY1. Airway preparations from the trachea, main bronchi, subsegmental bronchi and the parenchyma of rabbits were studied.2. The proximal airways, the trachea and main bronchi, were less sensitive to histamine than the distal airways of the subsegmental bronchi and lung parenchymal strip.3. The proximal airways were more sensitive to carbachol than the distal airways.4. These results may assist in the interpretation of airway responses in vivo.
A STUDY OF THE ANTI‐ULCER ACTIVITY OF DIAZEPAM AND OTHER TRANQUILLOSEDATIVES IN ALBINO RATS
Authors: Gupta M. B. , Nath R. , Gupta G. P. , Bhargava K. P. 
Published: June 2007

SUMMARY1. Anti‐ulcer and sedative effects of tranquillosedatives viz. benzodiazepines (diazepam, oxazepam and nitrazepam), barbiturate (phenobarbitone), phenothiazines (chlorpromazine, trifluoperazine and thioridazine) and butyrophenone (haloperidol) were compared in albino rats.2. Ulceration of the glandular stomach was induced by 2 h restraint at 4°C. Sedation was measured using the rotarod test.3. These tranquillosedatives showed dose dependent anti‐ulcer and sedative effects. The relative potency and therapeutic index (ratio between rotarod ED50 and anti‐ulcer ED50) of each drug were determined. Diazepam showed the highest therapeutic index (1.88).4. Diazepam significantly reduced the volume of gastric secretion, raised its pH and prevented the gastric ulcer formation in pylorus ligated rats but failed to prevent the acute duodenal ulceration induced by intramuscular injection of histamine or carbachol in guinea‐pigs and rats, respectively.5. These observations suggest that benzodiazepines (diazepam) are more suitable anti‐ulcer agents compared to barbiturate, phenothiazines and butyrophenone. The anti‐ulcer effect of diazepam is possibly due to a combination of sedative, anti‐anxiety and antisecretory actions.
EXTENDED THEORY OF THE EARLY DIFFUSION OF MULTIPLE INDICATORS: BOUNDS ON PERMEABILITY RATIOS, WITH APPLICATIONS TO INTESTINAL CAPILLARIES
Authors: Bass L. , Aisbett J. 
Published: June 2007

SUMMARY1. The determination of ratios of capillary permeabilities to multiple indicators is secured by constructing upper bounds on effects of early back‐diffusion following a single arterial injection. The analysis does not exclude highly extracted indicators, and it allows for effects of asymmetric blood‐tissue exchange and of tissue concentration gradients.2. The concept of flow limitation of uptake is delimited operationally.3. It is shown how to identify effects of heterogeneity of uptake for data sets extended over large ranges of rate of blood flow.4. These new methods are used to show, for several sets of previously published data from muscle, that back‐diffusion cannot change appreciably the permeability ratios determined previously without any quantification of back‐diffusion.5. The main application is to data published by Perry and Granger (1981) on the permeability of cat intestinal capillaries to raffinose and inulin. The permeability ratios deduced from these data imply paradoxically restricted diffusion; it is shown that this cannot be attributed to effects of back‐diffusion, heterogeneity of extraction, or of solvent drag. It is shown that the paradox is removed if tissue‐to‐blood permeability to raffinose is at least double the blood‐to‐tissue permeability, possibly as part of the active transport of sugars from the intestinal lumen.6. It is shown that corresponding results on permeability ratios in dog gastric capillaries are not paradoxical (against the standard of unrestricted diffusion) under symmetric permeability to raffinose.
SYSTEMIC AND REGIONAL HAEMODYNAMIC PROFILE OF CAPTOPRIL IN CONSCIOUS RABBITS WITH BILATERAL CELLOPHANE PERINEPHRITIS HYPERTENSION
Authors: Bolt Gert R. , Saxena Pramod R. 
Published: June 2007

SUMMARY1. The radioactive microsphere technique was used to study the systemic and regional haemodynamic effects of the converting enzyme inhibitor captopril (0.1, 0.3 and 1.0 mg/kg) 10 min after intravenous administration in conscious rabbits with bilateral cellophane perinephritis hypertension, an experimental model of hypertension associated with normal plasma renin levels.2. Captopril lowered arterial blood pressure as a result of a dose‐dependent decrease in total peripheral resistance. The fall in blood pressure was accompanied by an increase in cardiac output after the second and third dose of captopril; heart rate was not significantly altered.3. Captopril produced a generalized peripheral vasodilatation; the changes in vascular conductance being most pronounced in the kidneys, intestines and skin which resulted in a significant increase in blood flow to these vascular beds.4. The effective antihypertensive properties of captopril in this ‘low plasma renin’ model of hypertension and the uniform increase in vascular conductances produced by captopril, which antagonizes the generalized increase in vascular resistances that characterizes cellophane perinephritis hypertension, may indicate the involvement of an increased activity of the renin‐angiotensin system, possibly in tissues, such as the vascular wall and brain, in the maintenance of the elevated blood pressure in this hypertensive form.
EFFECT OF PROSTAGLANDIN E2 ON SERUM IRON AFTER ACUTE AND CHRONIC BLOOD LOSS
Authors: Al‐Waili Noori S. , AL‐Azzawi Hani T. 
Published: June 2007

SUMMARY1. The effect of prostaglandin E2 on serum iron of New Zealand rabbits subjected to acute and chronic blood loss is demonstrated.2. The results showed that acute blood loss was followed by significant elevation of serum iron when sera were tested on day three after the bleeding. With subcutaneous injection of 40μg/kg body weight of prostaglandin E2 for each 12 h of the experiment, acute blood loss was followed by a significant reduction in serum iron within the same period.3. Similar results were obtained after chronic blood loss when subcutaneous injection of 20 μg/kg body weight of prostaglandin E2 was used for each 12 h of the experiment.4. It could be concluded that the prostaglandin E2 causes marked lowering of serum iron following blood loss.
CORONARY AND PERIPHERAL VASCULAR RESISTANCE IN THE ANAESTHETIZED DIABETIC SHEEP
Authors: Hoffman Linda , Yong A. C. , Heath J. , Kilpatrick D. 
Published: June 2007

SUMMARY1. To determine whether vascular resistance was altered in diabetes, the vascular resistance in both the peripheral arterial bed and the circumflex coronary artery was compared in six normal and five diabetic adult sheep, under pentobarbitone anaesthesia. Diabetes induced by alloxan significantly increased blood glucose (15.6mmol/l, s.e.m. = 2.8, vs 5.5 mmol/l, s.e.m. =0.6; P>0.001) compared with controls.2. Systolic blood pressure was lower in diabetics (92 mmHg, s.e.m. = 12, vs 123 mmHg, s.e.m. =5; P<0.025) as was diastolic blood pressure (73 mmHg, s.e.m. = 15, vs 104 mmHg, s.e.m. =4; P > 0.05).3. Basal peripheral resistance was lower in diabetics than controls (36.0 mmHg. min/1, s.e.m. = 7.9, vs 42.3 mmHg.min/1, s.e.m. =2.8), but not significantly so.4. Methoxamine markedly increased peripheral vascular resistance in both groups, but did not change coronary vascular resistance, due to autoregulation. The dose‐response curves of peripheral or coronary arteries to methoxamine showed no significant difference between diabetic and control sheep. Dose‐response curves for isoprenaline and noradrenaline infusion suggested there may be altered β‐receptor sensitivity in diabetes.5. In conclusion, there are marked differences in the vascular beds of diabetic and normal sheep under basal conditions. In contrast to previous studies, α‐adrenoceptors are not different in diabetics, but further studies in unanaesthetized animals are indicated, as β‐receptor sensitivity may be altered in diabetes.
EFFECT OF PREGNANCY IN THE RABBIT ON THE PRESSOR RESPONSE TO ANGIOTENSIN AND NORADRENALINE
Authors: Joels N. , Humphreys P. W. 
Published: June 2007

SUMMARY1. The pressor responses to angiotensin II injections of 29, 117 and 468 pmol/kg and infusion at 54 pmol/kg per min were compared in near‐term pregnant and matched non‐pregnant rabbits. The responses to noradrenaline injections of 652, 2608 and 10 432 pmol/kg and infusion at 1185 pmol/kg per min were similarly compared.2. At all doses of angiotensin and noradrenaline, whether by injection or infusion, the response of the pregnant animals was significantly greater. However the control arterial pressures of the pregnant rabbits were lower and fell in a range where the baroreceptor reflex might be less effective. Thus less efficient buffering could contribute to the greater response to the vasoconstrictor agents.3. To test the effect of pregnancy on the vascular response to angiotensin and noradrenaline when reflex and central effects were excluded, hexamethonium was used to produce autonomic ganglion blockade. The response to both vasoconstrictors was now less in the pregnant rabbits than in the non‐pregnant.4. Thus in assessing the effects of pregnancy on the responses of the rabbit to angiotensin and noradrenaline the effect of pregnancy on mean blood pressure must be taken into account, since this can influence the extent to which the arterial baroreceptors may modulate the response.
STABILITY AND INTER‐RELATIONSHIPS OF HORMONE, HAEMODYNAMIC AND ELECTROLYTE LEVELS IN HEART FAILURE IN MAN
Authors: Fitzpatrick M. Andrew , Nicholls M. Gary , Ikram Hamid , Espiner Eric A. 
Published: June 2007

SUMMARY1. Relationships between clinical status, haemodynamic measurements, hormone and biochemical indices, and maintenance diuretic dose in patients with chronic cardiac failure, are not clear. This study assessed such relationships and their stability under standardized conditions in 21 hospitalized patients.2. The daily maintenance dose of frusemide correlated closely and in a positive fashion with plasma levels of renin activity, angiotensin II and aldosterone (P < 0.001), and to a lesser extent with plasma noradrenaline. Although there was some overlap, patients most incapacitated by their heart failure had the highest circulating levels of renin activity, angiotensin II, aldosterone and noradrenaline.3. Plasma aldosterone correlated closely with concomitant angiotensin II levels (r= 0.70, P < 0.001) but not with its other secretagogues ACTH (as reflected by plasma cortisol) or plasma potassium. Close positive correlations between angiotensin II and plasma levels of urea and creatinine (P < 0.01) were observed. Both renin and angiotensin I1 showed positive relationships with right heart pressures, but were inversely related to cardiac index and arterial pressure.4. These results show close relationships between clinical and haemodynamic indices on one hand, and hormones on the other. The renin‐angiotensin system appears to be the primary regulator of aldosterone under these conditions, and its activity relates closely to haemodynamic measurements and to the degree of azotaemia.
SOME CARDIOVASCULAR EFFECTS OF MONOAMINE OXIDASE INHIBITORS IN UNANAESTHETIZED RATS
Authors: Marwood John F. , Huston Vicki , Wall Kim T. 
Published: June 2007

SUMMARY1. The effects of four monoamine oxidase (MAO) inhibitors on the blood pressure of conscious normotensive and DOC‐salt hypertensive rats were measured. Harmaline (20 mg/kg p.o.), pargyline (100 mg/kg p.o.) and tranylcypromine (10 mg/kg p.o.) all lowered blood pressure significantly in both normotensive and hypertensive rats whereas methylaplysinopsin (10 mg/kg p.o.) had no effect on blood pressure.2. The effects of these MAO inhibitors on blood pressure responses to serotonin, tyramine and β‐phenylethylamine were determined in conscious normotensive rats. Pargyline and tranylcypromine shifted the dose‐response curves for tyramine and β‐phenylethylamine, but not serotonin, to the left, indicating inhibition of type B MAO. Harmaline and methylaplysinopsin shifted the dose‐response curves for tyramine and serotonin but not β‐phenylethylamine, to the left, indicating inhibition of type A MAO.3. Since the four antagonists tested inhibited at least one form of MAO, and yet not all of these MAO inhibitors lowered blood pressure, we suggest that our results are consistent with the view that the hypotensive action of MAO inhibitors is not necessarily related to inhibition of MAO.