bluuebunny/crossref_metadata_2025_split huggingface dataset:
THE RENIN‐ANGIOTENSIN SYSTEM AND HYPERTENSIVE LEFT VENTRICULAR HYPERTROPHY IN THE RAT
Authors: Newling R. , Fletcher P. J. , Duggin G. G. 
Published: June 2007

SUMMARY1. The relationship between left ventricle‐to‐body weight ratio (LV/BW), mean arterial pressure (MAP, the average of 12 h of intra‐arterial monitoring in conscious animals) and plasma renin activity (PRA) was assessed at 12 weeks after unilateral clipping or sham operation in twenty‐four one‐kidney rats and twenty‐six two‐kidney rats.2. The degree of hypertension and left ventricular hypertrophy were similar in one‐kidney and two‐kidney groups. There was a close linear relationship between LV/BW and MAP which was similar in one‐kidney and two‐kidney rats.3. PRA was significantly elevated only in two‐kidney rats and was not related to the degree of hypertrophy after accounting for the effect of PRA on MAP.4. These data suggest that activation of the renin‐angiotensin system does not contribute directly to myocardial hypertrophy in rats with renal‐clip hypertension.
SEROTONIN (5HT) AND ITS ANTAGONISTS: INVOLVEMENT IN THE CARDIOV ASCULAR SYSTEM
Authors: Marwood John F. , Stokes Gordon S. 
Published: June 2007

SUMMARYThe cardiovascular actions of serotonin and its antagonists are reviewed with a view to clarifying whether serotonin has a role in blood pressure control through actions on the peripheral vasculature. Serotonin has complex actions in the heart and vasculature but none of these actions is completely understood. There is no doubt, however, that serotonin has extensive interactions with the sympathetic nervous system. The nature of the serotonin receptor is also discussed. There is extensive evidence that more than one type of serotonin receptor exists. Biochemical studies in brain homogenates have delineated two sub‐populations of serotonin receptors, named 5HT1 and 5HT2. It is not clear whether the same receptor types exist in the vasculature but various actions of serotonin on the vasculature have tentatively been ascribed to actions on 5HT1‐ and 5HT2‐type receptors. It is clear that there is some functional overlap between serotonin‐receptors and α‐adrenoceptors. The mechanism by which this overlap could occur is unknown although we suggest it may result from a physical overlap of serotonin receptors and α‐adrenoceptors. Compounds which antagonize serotonin have provided the means for investigating serotonin receptors but have not clarified the role of serotonin in blood pressure control; certainly they have comparatively little effect on blood pressure and this may simply reflect the lack of free circulating serotonin. In animal studies the new serotonin antagonist ketanserin appears to lower blood pressure via α‐adrenoceptor blockade.
PERITONEAL DIALYSIS SOLUTIONS AND FELINE SPLANCHNIC BLOOD FLOW
Authors: Granger D. Neil , Ulrich Michele , Perry Michael A. , Kvietys Peter R. 
Published: June 2007

SUMMARY1. Splanchnic blood flow is generally considered to be one of the major factors governing the efficiency of peritoneal dialysis; however, few direct measurements of blood flow have been made during peritoneal dialysis.2. The radioactive microsphere technique was used to assess the effects of 1.5 and 4.25 g/100 ml dextrose‐Dianeal solutions on blood flow to various tissues in the abdominal cavity. The effects of dialysis solution on blood flow through the superior mesenteric and coeliac arteries were measured by electromagnetic flowmetry.3. The results indicate that the commercial peritoneal dialysis solutions dramatically increase blood flow to the mesentery, omentum, intestinal serosa and parietal peritoneum. These changes are not accompanied by significant alterations in blood perfusion in the major abdominal organs (liver, stomach, intestine, pancreas, spleen). Peritoneal dialysis solutions do not significantly alter blood flow through the coeliac and superior mesenteric arteries.4. These findings indicate that commercial dialysis solutions improve perfusion to the peritoneum without significantly altering splanchnic blood flow.
THE EFFECT OF VASOPRESSIN ON HEPATIC ARTERY FLOW IN THE RAT
Authors: Jenkins S. A. , Mooney B. , Devitt P. , Taylor I. , Shields R. 
Published: June 2007

SUMMARY1. The effects of vasopressin infusion on hepatic artery flow was studied in rats.2. Hepatic artery ligation followed by the infusion of vasopressin (0.08 μU/g body weight per min) decreases portal venous flow and liver blood flow.3. Vasopressin infusion results in an increase in hepatic artery flow and liver blood flow both of which are abolished by subsequent hepatic artery ligation.4. The increase in hepatic artery flow and the decrease in portal venous flow following the infusion of vasopressin is discussed in relation to the management of patients presenting with bleeding oesophageal varices.
EFFECTS OF METRONIDAZOLE ON INTESTINAL TRANSIT TIME AND FAECAL WEIGHTS OF HUMAN SUBJECTS
Authors: Kurpad A. V. , Shetty P. S. 
Published: June 2007

SUMMARY1. The combined administration of metronidazole and ampicillin increased faecal weights by 198% in normal male subjects on controlled diets with constant energy, protein and dietary fibre content.2. Intestinal transit times were unaltered despite marked increase in faecal weights.
POTENTIATION OF DEPRESSOR RESPONSES TO ARACHIDONIC ACID BY ANGIOTENSIN CONVERTING ENZYME INHIBITORS IN THE RAT
Authors: Hui S‐C. G. , Dai S. , Ogle C. W. 
Published: June 2007

SUMMARY1. In chloralose anaesthetized rats, intravenous administration of captopril, SQ 20881, SA 446 or MK 421 (0.5 mg/kg) potentiated the depressor responses to arachidonic acid 3 mg/kg given intravenously.2. Same doses of the above angiotensin converting enzyme inhibitors caused an approximately 100‐fold decrease in sensitivity to the pressor effects of angiotensin I, with a concomitant similar increase in sensitivity to the depressor effects of bradykinin.3. Depressor responses to arachidonic acid, both before and after administering the converting enzyme inhibitors, were abolished by intravenous indomethacin (5 mg/kg).4. These results suggest that increased synthesis of prostaglandins in the circulation may contribute to the hypotensive effect of the angiotensin converting enzyme inhibitors, a group of newly developed antihypertensive agents.
FAILURE OF NEOMYCIN TO MODIFY ACTH INDUCED HYPERTENSION IN SHEEP
Authors: Tresham Janette , Coghlan John P. , Denton Derek A. , Scoggins Bruce A. , Whitworth Judith A. 
Published: June 2007

SUMMARY1. Studies in rats have shown that neomycin administration attenuates certain types of adrenocortical steroid dependent hypertension, including ACTH hypertension.2. The effects of oral neomycin on ACTH induced hypertension were examined in conscious sheep.3. Neomycin has no effect on the blood pressure or metabolic responses to ACTH in sheep.
SEROTONIN IN TOXAEMIA OF PREGNANCY
Authors: Gujrati V. R. , Shanker K. , Parmar S. S. , Chandrawati S. Vrat , Bhargava K. P. 
Published: June 2007

SUMMARY1. Serotonin (5‐hydroxytryptamine) contents of maternal blood, fetal cord blood, and placenta from thirty‐five patients with toxaemia of pregnancy and forty normal pregnant subjects were estimated. Placental monoamine oxidase activity from ten normal and ten toxaemic cases were also estimated.2. An increased content and uptake of serotonin by platelets in maternal blood from toxaemic patients were observed and there was a concomitant reduction in platelet count.3. Raised levels of serotonin and a decrease in monoamine oxidase levels were observed in placentas of the toxaemic group.4. The levels of serotonin in fetal cord blood were significantly higher than those in normal maternal blood. It is suggested that the fetus could be the source of increased serotonin in this syndrome, due to the decrease in monoamine oxidase activity in the toxaemic placenta.5. An abnormality in indole amine metabolism may contribute to the pathology associated with toxaemia of pregnancy.
INFLUENCE OF PROSTAGLANDIN INHIBITION ON DIHYDRALAZINE INDUCED ACUTE EFFECTS IN PATIENTS WITH ESSENTIAL HYPERTENSION*
Authors: Heimann Ingrid W. , Ratge Dieter , Wisser Hermann , Frölich Jürgen C. 
Published: June 2007

SUMMARY1. In order to determine whether vasodilator prostaglandins (PG) contribute to the acute vascular and endocrine responses to intravenously administered dihydralazine, we examined its effects on systolic and diastolic blood pressure (BP), heart rate (HR), plasma renin activity (PRA) and the plasma catecholamines (CA) noradrenaline (NA), adrenaline (A) and dopamine (DA) as well as on sodium, potassium and creatinine clearance (CNa, CKand CCrrespectively), urinary flow rate, urinary catecholamines (NA, A, DA) and iPGE2and i6‐keto‐PGF1αexcretion rate in six patients (three females, three males) with essential hypertension before and after PG synthesis inhibition by the nonsteroidal, anti‐inflammatory agent diclofenac.2. Diclofenac, which reduced urinary iPGE2and i6‐keto‐PGF1α, excretion by 62% (P= 0.026) and 45% (P= 0.037), respectively, antagonized dihydralazine induced diastolic BP reduction (P= 0.0009), HR increase (P= 0.01), noradrenaline and adrenaline increase in plasma (P= 0.02 andP= 0.05, respectively), increase in urine flow rate (P= 0.03), sodium clearance (P= 0.01) and tended to reduce PRA.3. We conclude that dihydralazine‐mediated changes can be reduced by cyclooxygenase inhibition, most likely on the basis of a reduction of its effect on peripheral resistance, thereby leading to less reflex activation of the sympathetic nervous and renin‐angiotensin systems.
EFFECTS OF DOPAMINE ON RENAL FUNCTION IN THE RAT ISOLATED PERFUSED KIDNEY
Authors: McGrath Barry , Bode Karin , Luxford Ann , Howden Brian , Jablonski Paula 
Published: June 2007

SUMMARY1. The renal effects of dopamine, the dopamine antagonist spiperone and the combination of dopamine and spiperone were examined in the isolated perfused rat kidney preparation. Studies were carried out at constant perfusion pressure and the following were measured at 10 min intervals for 1 h: perfusate flow; GFR (3H‐inulin); urine flow rate; sodium, potassium and kallikrein excretion; perfusate renin concentration; perfusate and urinary‐dopamine levels.2. Low‐dose dopamine infusion (6 × 10‐10 mol/min) resulted in significant diuresis, natriuresis and kaluresis but little change in GFR. These effects were blocked by spiperone (10‐10 mol/min) which had no significant effects when infused alone.3. At a higher dose (10‐8 mol/min) dopamine significantly increased urine flow alone; this too was reversed by spiperone.4. Dopamine had no significant effects on perfusate flow, renin release or kallikrein excretion.5. Perfused control kidneys excreted amounts of dopamine (328 pmol/h, s.e.m. = 57, n= 6) far in excess of kidney dopamine content (49 pmol/g, s.e.m. = 6, n= 32). Renal handling of infused dopamine was dose‐related; the fraction of the administered dose taken up and/or metabolized by the kidney on the higher dose infusion was considerably less than on the lower dose (40%, s.e.m. = 3 vs. 82%, s.e.m. = 6) while more was excreted (13%, s.e.m. = 3 vs. 2%, s.e.m. = 1).6. These studies indicate that dopamine at low doses can produce diuresis, natriuresis and kaluresis independently of extrarenal or haemodynamic influences and not mediated by renal renin or kallikrein systems. The kidney also exhibits a saturable capacity for dopamine uptake and/or metabolism.
ANTICHOLINESTERASE ACTIVITY OF AND POSSIBLE ION‐CHANNEL BLOCK BY CIMETIDINE, RANITIDINE AND OXMETIDINE IN THE TOAD ISOLATED RECTUS ABDOMINIS MUSCLE
Authors: Cheah L. S. , Lee H. S. , Gwee M. C. E. 
Published: June 2007

SUMMARY1. Responses of the toad isolated rectus abdominis muscle to cumulative doses of acetylcholine were recorded in the absence or presence of varying concentrations of cimetidine, ranitidine or oxmetidine. The corresponding cumulative log concentration‐response curves for acetylcholine were then plotted for each antagonist studied.2. Cimetidine (5 mmol/1), ranitidine (1 mmol/1) and oxmetidine (0.02 mmol/1) potentiated the effect of acetylcholine by 4‐fold, 2.6‐fold and 1.3‐fold, respectively.3. At higher concentrations all three histamine H2‐receptor antagonists produced a concentration‐dependent and non‐parallel shift of the acetylcholine curve to the right of the corresponding control curve accompanied by a depression of the maximal response.4. The results provide further evidence that the H2‐antagonists studied possess anticholinesterase activity and also suggest that the H2‐antagonists may produce neuromuscular blockade by ion‐channel block. The clinical implications of the results obtained are also discussed.
CONTINUOUS 24‐HOUR INTRA‐ARTERIAL BLOOD PRESSURE RECORDING IN THE CONSCIOUS UNRESTRAINED RABBIT
Authors: Sneek J. H. J. , Eijzenbach V. , Ligtenberg A. C. M. , Borst C. 
Published: June 2007

SUMMARY1. A measuring system is described for the long‐term continuous beat‐to‐beat measurement of mean aortic pressure and heart period (interval between beats) in the conscious unrestrained rabbit. Pressures and heart periods were collected in hourly histograms. The histograms were summed into day (0800–2000 h), night (2000–0800 h) and 24‐hour histograms. Separate histograms were formed for resting and active periods. From each histogram the mean value, standard deviation, fifth percentile, 50th percentile and 95th percentile were calculated and stored on a floppy disc together with the histograms. Off‐line, histograms and their descriptive parameters were plotted and sent to a HP 1000 computer for bulk storage and further analysis.2. The measuring system is capable of handling up to eight animals simultaneously for an indefinite period.3. The design functioned properly in the long‐term measurement (more than 4 weeks) of mean level and variability of arterial pressure and heart period. The measuring system is useful in the study of arterial blood pressure behaviour after sino‐aortic denervation and in the evaluation of drug effects in conscious animals.
EFFECTS OF NEUROTOXIN‐INDUCED BRAINSTEM LESIONS ON THE RESPIRATORY RESPONSES OF CONSCIOUS RATS
Authors: Martin‐Body R. L. , Grundy H. R. 
Published: June 2007

SUMMARY1. Respiration was recorded in unanaesthetized rats breathing air, or CO2 in air, 4–8 days after injection into the rostral brainstem at the level of the dorsal raphe nucleus of either a catecholaminergic neurotoxin, a serotoninergic neurotoxin, or the vehicle (0.5% ascorbic acid) of these drugs. Some rats were pretreated with the noradrenergic neurone protecting agent, desmethylimipramine (DMI).2. Vehicle injection resulted in an increase in the frequency (f) sensitivity to CO2. In two of four cases, injection of 6‐hydroxydopamine caused a similar response but in the remaining cases injections caused increases in inspiratory duration (TI), expiratory duration (TE) and tidal volume (VT) during air‐breathing.3. The serotonergic neurotoxin, 5,7‐dihydroxytryptamine, reduced the frequency sensitivity to CO2 significantly. This reduction was not sustained. In all cases air‐breathing f was decreased due to a prolongation of TI; in most cases air‐breathing VT was increased. The characteristic effect of midline 5,7‐dihydroxytryptamine lesions was an increase in the VT sensitivity to CO2.4. On the basis of the results, it is proposed that noradrenaline is essential to the processes determining basic respiratory rhythm, whereas dopamine and serotonin are important inhibitors in chemoreflex ventilatory patterns.
THE INTERACTION OF EPHEDRINE WITH β‐ADRENOCEPTORS IN TRACHEAL, CARDIAC AND SKELETAL MUSCLES
Authors: Waldeck Bertil , Widmark Erik 
Published: June 2007

SUMMARY1. Three β‐adrenoceptor mediated effects were measured in vitro on tissues from guinea‐pig: (a) relaxation of the trachea (mainly β2), (b) increase in the force of contraction of the papillary muscle (β1), and (c) depression of the subtetanic contractions of the soleus muscle (β2).2. The relaxant effect of ephedrine on the trachea was weak but was resistant to reserpine pretreatment. There was no appreciable agonistic effect of ephedrine on the soleus muscle.3. Ephedrine per se had a marked positive inotropic effect on the papillary muscle with a pD2 of about 6.0. This effect disappeared completely after pretreatment with reserpine.4. Ephedrine inhibited the response to isoprenaline. The apparent pA2 was about 4.8 in all tissues studied.
GANGLION BLOCKING ACTIVITY OF CIMETIDINE IN THE ANAESTHETIZED CAT
Authors: Gwee M. C. E. , Cheah L. S. , Lee H. S. 
Published: June 2007

SUMMARY1. Cimetidine produced a dose‐dependent and reversible inhibition of contractions of the nictitating membrane elicited through stimulation of the preganglionic nerve supplying the superior cervical ganglion in the anaesthetized cat. Postganglionic nerve stimulation resulted in only a slight and variable inhibition of the contractions. Both hexamethonium and cimetidine also produced a dose‐dependent and reversible fall in arterial blood pressure.2. The ganglion blocking activity of cimetidine was much weaker than that of hexamethonium; the ED50 ratio (cimetidine:hexamethonium) calculated from the cumulative log dose‐response curves for the two drugs was 64.3. The possible mechanism(s) of ganglion blockade produced by cimetidine is discussed including a possible action at nicotinic receptors, either directly or indirectly (via its anticholinesterase activity), and ion channel blockade.4. The clinical implications of cimetidine‐induced ganglionic blockade are also discussed, especially with respect to sexual impotence associated with the use of cimetidine.
METOCLOPRAMIDE ENHANCES BETHANECHOL‐INDUCED PANCREATIC EXOCRINE SECRETION OF THE DOG
Authors: Yamagishi F. , Haruta K. , Homma N. , Iwatsuki K. , Chiba S. 
Published: June 2007

SUMMARY1. The effects of metoclopramide on pancreatic exocrine secretion were investigated in the pentobarbitone‐anaesthetized dog. All drugs were injected into the femoral vein.2. Metoclopramide (10–1000 μg/kg) did not change the resting rate of pancreatic secretion.3. Pancreatic secretion, induced by bethanechol (3 μg/kg), was dose‐dependently enhanced by simultaneous injections of metoclopramide (10 and 30 μg/kg), but the protein and bicarbonate concentrations of the pancreatic juice were not affected. Secretions induced by secretin (0.1 units/kg) and dopamine (3 μg/kg) were not modified by metoclopramide at up to 30 μg/kg.4. A larger dose of metoclopramide (1000 μg/kg) suppressed dopamine‐induced secretion to a lesser extent than the same dose of sulpiride.5. From these results, it is concluded that metoclopramide enhances secretory responses to cholinergic stimulations by peripherally sensitizing the muscarinic receptor‐mediated exocrine process and this drug is a weaker antagonist of the dopamine D2 receptors than sulpiride.
EFFECTS OF ENERGY AND PROTEIN RESTRICTION ON ACETYLCHOLINE SENSITIVITY OF RAT ISOLATED PERFUSED HEART
Authors: Venkataraman B. V. , Shetty P. S. , Joseph Thangam , Arifullah H. Mohamed , Stephen P. M. 
Published: June 2007

SUMMARY1. Responses to acetylcholine of isolated perfused hearts obtained from rats which were acutely starved, chronically half‐starved or protein‐restricted were compared with those of paired control groups.2. Isolated hearts of totally starved rats showed no significant change in the responses elicited by 10 and 20 μg doses of acetylcholine as compared with paired controls. With 40 μg acetylcholine a significantly greater reduction (P < 0.001) in heart rate and coronary flow was seen and the duration of the negative chronotropic action was significantly increased (P < 0.05), as compared with controls.3. Isolated hearts of half‐starved and protein‐restricted rats responded to 10, 20 and 40 μg doses of acetylcholine with significantly greater reduction (P < 0.001) in heart rate, coronary flow and increase in duration of negative chronotropic action (P < 0.001) as compared to controls.
EFFECTS OF THE INTRAPERITONEAL ADMINISTRATION OF DIAZEPAM ON RAT SERUM LIPOPROTEINS SEPARATED BY POLYACRYLAMIDE GEL ELECTROPHORESIS
Authors: Cuparencu B. , Tomus C. , Horák J. , Nan A. , Cordos M. , Puia L. , A M. , Marino E. 
Published: June 2007

SUMMARY1. In normolipidaemic young rats the intraperitoneal administration of diazepam (10 mg/kg) induced a marked fall of the total serum lipids and total cholesterol. A dose of 5 mg/kg brought about an increase of HDL2 lipoprotein fraction and an elevation of the HDL2/HDL2.HDL3 ratio.2. Margarine administration elicited a significant augmentation of the total serum lipids and a reduction of the HDL2/HDL2.HDL3 ratio. The intraperitoneal injection of diazepam in margarine‐treated rats brought about a decrease of total serum lipids and total cholesterol, (when compared to the margarine values), an obvious elevation of the HDL2 fraction and of HDL2/HDL2.HDL3 ratio. The LDL, (β) fraction was decreased.3. These data confirm our earlier findings which show that diazepam improves the HDL cholesterol/total cholesterol ratio.
ACTIVE AND INACTIVE RENIN IN CRITICALLY ILL PATIENTS
Authors: Thatcher Robin , Butty Jill S. , Whitworth Judith A. , Fei David T. W. , Skinner Sandford L. 
Published: June 2007

SUMMARY1. The relationship between active (A) and inactive (I) plasma renin concentrations (PRC) was examined in critically ill patients to test for intravascular renin activation in states of shock and tissue damage.2. Critically ill patients had significantly elevated APRC and lowered IPRC:APRC ratio compared with age and sex matched healthy subjects. IPRC in the critically ill was similar to the control group.3. During blood donation normal volunteers showed a twofold increase in APRC. The rise in APRC was proportionately greater than for IPRC, with a subsequent fall in IPRCAPRC ratio.4. In both critically ill patients and blood donors elevated APRC was associated with decreased IPRC:APRC ratio, consistent with either consumption of the inactive renin zymogen or preferential secretion of the active form. Individual critically ill patients displayed markedly depressed ratios but with only moderately elevated APRC, a pattern suggestive of intravascular renin activation. Consistent evidence for intravascular or extravascular activation of renin was not apparent.
INHIBITION OF ACETYLCHOLINESTERASE BY HISTAMINE AGONISTS AND ANTAGONISTS
Authors: Lee H. S. , Cheah L. S. , Gwee M. C. E. 
Published: June 2007

SUMMARY1. The histamine H1 and/or H2‐receptor agonists showed weak acetylcholinesterase inhibitory activity. Their dissociation constants (Kis and/or Kii) were 2‐methyl histamine (Kis= 1751 μmol/1, s.e. = 163) < 4‐methyl histamine (Kis= 3551 μmol/1, s.e. = 414) < dimaprit (Kis= 2931 μmol/1, s.e. = 605; Kii= 3668 μmol/1, s.e. = 901) < histamine (Kis= 6480 μmol/1, s.e. = 1360).2. Both histamine H1 and H2‐receptor antagonists showed stronger acetylcholin‐esterase inhibitory activity. Their dissociation constants were ranitidine (Kii= 1.56 μmol/1, s.e. = 0.14) ≪ oxmetidine (Kis= 14.7 μmol/1, s.e. = 1) < mepyramine (Kis= 178 μmol/1, s.e. = 23; Kii= 440 μmol/1, s.e. = 98) < cimetidine (Kis= 199 μmol/1, s.e. = 12; Kii= 827 μmol/1, s.e. = 126).3. Using the ROSFIT programs for fitting data to common enzyme kinetic models, the inhibition caused by histamine, 4‐methyl histamine, 2‐methyl histamine, oxmetidine and neostigmine was of the competitive type. Mepyramine, cimetidine and dimaprit appeared to exhibit the modern non‐competitive type of inhibition with their primary action on the enzyme rather than on the enzyme‐substrate complex. Ranitidine seemed to act on the enzyme‐substrate complex rather than the enzyme, conforming to the uncompetitive inhibition model.4. The clinical implications of acetylcholinesterase inhibition by cimetidine and ranitidine are discussed.