bluuebunny/crossref_metadata_2025_split huggingface dataset:
RENAL INTERACTION OF ATRIAL NATRIURETIC PEPTIDE WITH ANGIOTENSIN II: GLOMERULAR AND TUBULAR EFFECTS
Authors: Rakugi Hiromi , Ogihara Toshio , Nakamaru Mitsuaki , Saito Hiroshi , Shima Junko , Sakaguchi Katsuhiko , Kumabara Yuichi 
Published: June 2007

SUMMARY1. The possible interactions between the renal effects of atrial natriuretic peptide (ANP) and angiotensin II (All) were studied in normal sodium‐replete human subjects. Recent investigations have suggested that ANP inhibits the pressor and volume‐retaining effects of activation of the renin‐angiotensin system. Thus, ANP may attenuate the effects of All on renal haemodynamics or tubular transport.2. ANP (0.1 μg/kg per min, 60 min) was intravenously infused into eight normal human subjects with and without pretreatment with enalapril (20 mg, per oral), an inhibitor of the converting enzyme, and during infusion of All (10 mg/kg per min).3. ANP infusion alone caused increases in the urine volume (from 96 ± 23 to 229 ± 44 mL/h, P < 0.05) and urinary sodium excretion (from 11.5 ± 1.6 to 20.9 ± 4.2 mEq/h, P < 0.05). These changes were accompanied by an increase in the glomerular filtration rate (from 127 ± 9 to 158 ± 9 mL/min, P < 0.05). ANP infusion after enalapril administration lowered the mean blood pressure (from 76 ± 2 to 71 ± 3 mmHg, P < 0.05) to a level similar to that observed during ANP infusion alone (from 84 ± 2 to 74 ± 2 mmHg, P < 0.01), but did not result in a significant diuresis (from 139 ± 23 to 174 ± 51 mL/h) or natriuresis (from 19.7 ± 2.5 to 14.3 ± 3.4 mEq/h, P < 0.05). This combined treatment with a converting enzyme inhibitor and ANP reduced both the glomerular filtration rate (160 ± 9 to 141 ± 10 mL/min) and the renal plasma flow (from 775 ± 49 to 570 ± 45 mL/min, P < 0.01).4. The antinatriuretic effects of exogenous All were reversed by superimposed ANP infusion (urinary sodium excretion: from 4.8 ± 1.0 to 24.3 ± 5.2 mEq/h, P < 0.01). Under these conditions, the glomerular filtration rate increased (from 114 ± 6 to 156 ± 7 mL/min, P < 0.05) to levels similar to those observed with ANP infusion alone. In addition the increased tubular sodium reabsorption induced by All was inhibited by concomitant ANP infusion (fractional proximal tubular sodium reabsorption: from 90.7 ± 3.5 to 80.3 ± 16.6%, P < 0.05, fractional post‐proximal tubular sodium reabsorption: from 91.5 ± 9.8 to 87.6 ± 8.8%, P < 0.05).5. These results suggest that ANP interacts with endogenous All particularly in the glomerulus, to cause a diuresis and natriuresis, and also suggest that ANP inhibits All‐induced tubular sodium reabsorption.
DOPAMINE RECEPTOR BLOCKING ACTION OF A DIBENZOTHIEPIN DERIVATIVE ISOFLOXYTHEPIN IN RATS
Authors: Yamada K. , Matsuo N. , Nagashima M. , Kumagai M. , Furukawa T. 
Published: June 2007

SUMMARY1. Subcutaneous injection of isofloxythepin or haloperidol inhibited exploratory behaviour, methamphetamine (3 mg/kg)‐induced hyperactivity and bromocriptine (15 mg/kg)‐induced yawning, and also elicited catalepsy.2. Isofloxythepin and haloperidol increased concentrations of dihydroxyphenyl‐acetic acid in the striatum and elevated serum prolactin levels.3. The results suggest that isofloxythepin, as well as haloperidol, blocks the action of the dopamine D2‐receptors in the striatum, nucleus accumbens and pituitary.
EVIDENCE THAT INCREASES IN CIRCULATING CATECHOLAMINES OF ADRENAL ORIGIN ARE NOT INVOLVED IN PRESSOR RESPONSE TO BILATERAL CAROTID OCCLUSION IN ANAESTHETIZED DOGS
Authors: Brassard Martine , Yamaguchi Nobuharu 
Published: June 2007

SUMMARY1. We studied whether or not circulating catecholamines of adrenal origin play a major role in cardiovascular responses evoked by bilateral carotid artery occlusion (3 min) in anaesthetized dogs.2. In the control group, the following parameters increased significantly (P < 0.05) during bilateral carotid occlusion: aortic systolic pressure, heart rate, net adrenal catecholamine output, net renal noradrenaline output, and plasma catecholamine concentrations in aortic blood. Similar responses were obtained during the second occlusion performed approximately 25 min after the first occlusion.3. After functional adrenalectomy (ADRX: diversion of adrenal venous blood flow), the increase in aortic adrenaline concentration observed during bilateral carotid occlusion was abolished. The increase in aortic noradrenaline concentration during the occlusion was significantly attenuated by approximately 60% (P < 0.01) after ADRX.4. The increase in net renal noradrenaline output during bilateral carotid occlusion after ADRX was not different from that observed before ADRX. Similarly, the response of aortic systolic pressure and heart rate during the occlusion was unaffected by ADRX. Furthermore, the increase in net adrenal catecholamine output during the occlusion was not affected by ADRX itself.5. From these results, we conclude that the increase in circulating catecholamines of adrenal origin during bilateral carotid occlusion is not a major determinant for the increases in aortic pressure and heart rate. The results suggest that these cardiovascular responses during the occlusion are mediated principally by neuronal noradrenaline released from peripheral sympathetic nerve terminals.
INHIBITION OF VASOCONSTRICTION BY PLATELET ACTIVATING FACTOR IN THE IN SITU BLOOD PERFUSED RAT MESENTERY
Authors: Gerkens John F. 
Published: June 2007

SUMMARY1. Perfusion pressure was measured in the in situ mesentery of anaesthetized rats perfused with blood at a constant 2 mL/min.2. Increases in perfusion pressure were produced by mesenteric peri‐arterial nerve stimulation at 10 Hz for 5 s at 2 min intervals and by bolus intra‐arterial injections of the vasoconstrictors noradrenaline, angiotensin II and 5‐hydroxytryptamine.3. The intra‐arterial infusion of platelet‐activating factor (PAF) to produce a blood concentration of 3 × 10−10 mol/L inhibited all responses to a similar extent. Intra‐arterial prazosin (1–5 × 10−9 mol/L), however, preferentially reduced responses to nerve stimulation and noradrenaline.4. PAF at concentrations from 3 × 10−11 to 10−9 mol/L produced increasing inhibition of vasoconstrictor responses to nerve stimulation. The dose‐response to PAF was shifted to the right by the concomitant intra‐arterial infusion of the PAF antagonist SRI 63–441.5. PAF at very low concentrations in vivo inhibits mesenteric vasoconstriction, produced by sympathetic nerve stimulation or various agonists, by a PAF‐receptor mediated vasodilatation of the mesenteric vasculature.
CHARACTERIZATION OF SINGLE HEART CELL CONTRACTILITY BY RAPID IMAGING
Authors: Delbridge Leanne M. , Harris Peter J. , Morgan Trefor O. 
Published: June 2007

SUMMARY1. A rapid imaging technique with temporal resolution of about 1 ms was employed to describe cell‐length changes during the isotonic contraction cycle of adult rat ventricular myocytes at 22°C.2. Parameters of cell contraction and relaxation were defined and values obtained under control conditions and after treatment with 5 μmol/L verapamil.3. Over 15 min, verapamil dramatically reduced the maximum shortening attained. This was associated with delay in both excitation‐contraction coupling latency and the time at which maximum rate of shortening occurred. However, peak shortening was recorded earlier in the contraction cycle. Total cell‐cycle time was abbreviated under the influence of verapamil and maximum rates of shortening and lengthening were depressed in a similar manner.4. The results highlight the value of improved temporal precision in describing myocyte contractility and validate the use of the parameters defined in the single‐cell model for the study of the mechanisms of action of cardiotonic agents.
NATRIURETIC AND HYPOTENSIVE EFFECTS OF BRAIN NATRIURETIC PEPTIDE IN ANAESTHETIZED DOCA‐SALT HYPERTENSIVE RATS
Authors: Kita Toshihiro , Kida Osamu , Kato Johji , Nakamura Shigeru , Eto Tanenao , Minamino Naoto , Kangawa Kenji , Matsuo Hisayuki , Tanaka Kenjiro 
Published: June 2007

SUMMARY1. Both natriuretic and hypotensive effects of brain natriuretic peptide (BNP), a novel peptide identified in porcine brain, were investigated in anaesthetized DOCA‐salt rats and control rats.2. An intravenous injection of two different doses (0.5 and 5.0 nmol/kg) of BNP produced a rapid and marked natriuresis and hypotension in DOCA‐salt rats.3. In particular, significant differences of responsiveness were observed between DOCA‐salt and control rats when administered the lower dose of BNP.4. It was suggested that DOCA‐salt rats might be relatively more susceptible to BNP.
EFFECT OF COLFORSIN ON HUMAN NEUTROPHIL SUPEROXIDE PRODUCTION AND INTRACELLULAR CALCIUM MOBILIZATION
Authors: Furui Hidehiko , Suzuki Kenji , Takagi Kenzo , Satake Tatsuo 
Published: June 2007

SUMMARY1. The effects of dibutyryl cyclic AMP (cAMP), isoproterenol and colforsin (forskolin) were evaluated on respiratory burst in human polymorphonuclear neutrophils (PMN).2. Dibutyryl cAMP showed a dose‐dependent inhibition of n‐formyl‐methionyl‐leucyl‐phenylalanine (FMLP)‐induced superoxide production by human PMN.3. Administration of isoproterenol induced a dose‐dependent inhibition of FMLP‐induced superoxide production by human PMN, and the inhibition was blocked by propranolol.4. Administration of colforsin induced a dose‐dependent inhibition of FMLP‐induced superoxide production by human PMN, and the inhibition could not be blocked by propranolol.5. Incubation with colforsin caused a significant increase in the cAMP level in human PMN.6. Pretreatment with colforsin caused a dose‐dependent inhibition in the elevation of intracellular free calcium (monitored by fura‐2 fluorescence), which was observed in human PMN stimulated with FMLP.7. These results suggest that cAMP is an inhibitory factor of superoxide production and intracellular calcium mobilization in human PMN stimulated with FMLP.
ENDOTHELIN RECEPTORS IN RAT ADRENAL GLAND VISUALIZED BY QUANTITATIVE AUTORADIOGRAPHY
Authors: Kohzuki Masahiro , Johnston Colin I. , Chai Siew Yeen , Casley David J. , Rogerson Fraser , Mendelsohn Frederick A. O. 
Published: June 2007

SUMMARY1. The radioligand [125I]‐endothelin was used to map receptors for endothelin in rat adrenal gland using in vitro autoradiography and computerized densitometry.2. In the adrenal, a high density of binding was found in the adrenal medulla (binding affinity constant 0.18 ± 0.11 × 109M−1) and zona glomerulosa (binding affinity constant 0.18 ± 0.07 × 109M−1). Binding was low to undetectable in the zona fasciculata and zona reticularis. Unrelated peptides did not displace endothelin.3. These results provide evidence of endothelin receptor distribution in adrenal gland and suggest that endothelin might exert multiple actions in the adrenal gland on catecholamine and aldosterone biosynthesis and secretion.
REPRODUCIBILITY OF 24‐HOUR NON‐INVASIVE AMBULATORY BLOOD PRESSURE MONITORING USING THE SUNTECH ACCUTRACKER
Authors: Torre L. B. , Rouse I. L. , Beilin L. J. 
Published: June 2007

SUMMARY1. The reproducibility of 24‐hour non‐invasive ambulatory blood pressure monitoring (ABPM) using the ‘Accutracker’ (AC) (Suntech Medical Instruments, NC) was determined to evaluate the AC's suitability for clinical trials investigating the effects of environmental determinants on blood pressure.2. Six healthy males from the University Department of Medicine underwent 24 h ABPM on the same working day of the week on six occasions. Reproducibility of hourly mean systolic blood pressure (SBP) and diastolic blood pressure (DBP) was determined using analysis of variance.3. No familiarization effect of measurement with the AC was detected.4. When comparing four time periods (0000–0759 h, 0800–1259 h, 1300–1859 h and 1900–2359 h), reproducibility of SBP was highest during the afternoon (1300–1859 h) whereas reproducibility of DBP was highest during late morning (0800–1259 h).5. Hourly mean SBP was significantly lower during late morning (0800–1259 h) than in the afternoon (1300–1859 h) or at night (1900–2359 h). Hourly mean SBP and DBP was significantly lower during sleep.6. Based on a select sample of volunteers, the AC is suitable for clinical trials involving paired measurements, particularly between 0800 and 1900 h when only 10–15 subjects would provide 80% power to demonstrate a 5 mmHg difference in SBP and DBP significant at the 0.05 level.
NIFEDIPINE BLOCKS ACTH AND CORTISOL RELEASE IN MAN
Authors: Jackson Richard V. , Jackson A. Jane , Grice Jeffrey E. , Vella Rodney D. 
Published: June 2007

SUMMARY1. The present study investigated the effect of prior administration of nifedipine on AVP‐induced ACTH release in seven normal volunteers. Three protocols were used: 20 mg oral nifedipine; 0.14 pressor units intramuscular (i.m.) per kg bodyweight aqueous AVP; oral nifedipine plus i.m. AVP 90 min later. Plasma ACTH and cortisol were measured at intervals for 2.5 h during each test.2. The mean peak plasma ACTH and cortisol levels and the mean peak changes from basal in these levels were significantly lower in the nifedipine/AVP test than in the AVP alone test. The integrated area under the cortisol time curve was significantly lower for the nifedipine/AVP test than that for the AVP test alone. Nifedipine alone caused no changes in ACTH or cortisol.3. Acute administration of oral nifedipine caused an inhibition of AVP‐stimulated ACTH and cortisol release in normal humans. This effect may be due to blockade of plasma membrane calcium channels normally activated during AVP stimulation of pituitary corticotrophs.
UNEXPECTED INCIDENCE OF LOW BLOOD PRESSURE 2 YEARS AFTER UNILATERAL ADRENALECTOMY FOR PRIMARY ALDOSTERONISM
Authors: Gordon Richard D. , Hawkins Peter G. , Hamlet Stephen M. , Tunny Terry J. , Klemm Shelley A. , Backmann Anthony W. , Finn Wendy L. 
Published: June 2007

SUMMARY1. Serial observations of blood pressure after unilateral adrenalectomy for aldosterone‐producing adenoma revealed an incidence of hypotension (systolic BP < fifth percentile for age‐ and sex‐matched normal population) of 27% at 2 years, more than 5 times that predicted.2. Serial observations of volume regulatory hormones showed significantly raised mean levels of plasma renin activity consistent with hypovolaemia. Significantly reduced mean aldosterone levels despite significantly raised mean plasma renin activity levels may reflect reduced responsiveness of the remaining adrenal.3. Reduction of significantly elevated preoperative ANP levels to significantly reduced levels postoperatively is also in keeping with postoperative hypovolaemia.4. A 50% reduction in plasma adrenaline after unilateral adrenalectomy might contribute to reduced noradrenergic activity (prejunctional β‐receptor) and reduced blood pressure, but plasma noradrenaline did not fall significantly postoperatively.5. Postoperative levels of renin, aldosterone, adrenaline and noradrenaline were not significantly different between those who did, and those who did not, become hypotensive.
MAGNESIUM SUPPLEMENTATION IN MILD HYPERTENSIVE PATIENTS ON A MODERATELY LOW SODIUM DIET
Authors: Nowson C. A. , Morgan T. O. 
Published: June 2007

SUMMARY1. The effect of oral magnesium supplementation was assessed in a group of untreated, mild hypertensive subjects who were following a moderately low sodium diet (baseline urinary sodium 86 ± 6 mmol/day).2. Thirteen patients were allocated placebo and 12 were allocated magnesium aspartate (10 mmol/day) in a double blind fashion for 8 weeks.3. There was no fall in blood pressure with magnesium supplementation and no significant difference in blood pressure between groups at the end of the study.4. In the magnesium group there was an increase in urinary magnesium (4.4 ± 0.6 to 6.1 ± 1 mmol/day P < 0.001), and urinary calcium (4.3 ± 0.7 to 5.5 ± 0.9 mmol/day P < 0.01). There was no change in plasma or red cell magnesium or plasma renin activity with supplementation.5. Magnesium supplementation does not appear to have an additive hypotensive effect in mild hypertensive subjects on a reduced sodium intake.
AN IN VITRO STUDY OF INTERACTIONS BETWEEN DOXAZOSIN AND ENALAPRILAT AT VASCULAR α1‐ADRENOCEPTORS
Authors: Tierney Garth , Marwood John , Stokes Gordon 
Published: June 2007

SUMMARY1. Isolated perfused male Sprague‐Dawley rat tail artery segments were used to investigate interactions between the α‐1‐adrenoceptor antagonist, doxazosin, and the angiotensin converting enzyme (ACE) inhibitor, enalaprilat, using phenylephrine (PE) as the α1‐adrenoceptor agonist.2. In concentrations of up to 10–5 mol/L, enalaprilat had no effect on arterial responses to PE.3. Doxazosin produced a concentration‐dependent competitive α1‐adrenoceptor antagonism, yielding a mean pA2 value of 8.72.4. In the continuous presence of 10−6 mol/L enalaprilat, doxazosin with a pA2 value of 9.10 was a 2.4‐fold more potent α1‐adrenoceptor antagonist than in the absence of enalaprilat.5. These results are interpreted to indicate that endogenously produced angiotensin II can modulate the activity of α1‐adrenoceptors in vascular smooth muscle.
INHIBITION OF TRANSMITTER RELEASE FROM SYMPATHETIC NERVE ENDINGS BY ω‐CONOTOXIN
Authors: Brock J. A. , Cunnane T. C. , Evans R. J. , Ziogas J. 
Published: June 2007

SUMMARY1. The effects of the calcium channel blocker, ω‐conotoxin, on sympathetic neuroeffector function in the guinea‐pig vas deferens have been investigated using a combination of mechanical and electrophysiological recording techniques.2. Diphasic contractions evoked by electrical field stimulation were irreversibly abolished by ω‐conotoxin (10–100 nmol/L).3. Electrically evoked excitatory junction potentials and currents were irreversibly blocked by ω‐conotoxin (10–100 nmol/L). Spontaneous excitatory junction potentials and currents were unaffected by this treatment.4. ω‐Conotoxin did not block impulse propagation in the nerve terminals. However, in three of four experiments ω‐conotoxin caused a decrease in the size of the nerve terminal impulse.5. These findings support the suggestion the co‐conotoxin acts prejunctionally to inhibit sympathetic neuroeffector by interfering with depolarization‐secretion coupling.
DILATATION OF THE RIGHT ATRIUM STIMULATES PHOSPHATIDYLINOSITOL TURNOVER
Authors: von Harsdorf Rüdiger , Lang Rudolph E. , Woodcock Elizabeth A. 
Published: June 2007

SUMMARY1. Dilatation of the rat right atria caused a stimulation of the phosphatidylinositol turnover pathway as measured by an increase in the accumulation of inositol phosphates in isolated, perfused hearts.2. In right atria, increases were detected after 1 min dilatation and maximal increases were observed after 10 min. Dilatation for 10 min caused an increase in inositol monophosphate inositol bisphosphate and inositol trisphosphate from 23.3 ± 0.9, 15.4 ± 0.4, and 9.5 ± 0.3 (mean and s.e.m., n= 7 ct/min per mg tissue) to 74.6 ± 2.3, 20.2 ± 1.3 and 13.6 ± 1.5 (n= 8), respectively (P < 0.01 for all inositol phosphates.)3. These results show that the myocardium can respond to dilatation by an activation of the phosphatidylinositol turnover pathway.
OBSERVATIONS ON A NEW NON‐INVASIVE MONITOR OF SKIN BLOOD FLOW
Authors: Hales J. R. S. , Stephens F. R. N. , Fawcett A. A. , Daniel K. , Sheahan J. , Westerman R. A. , James S. B. 
Published: June 2007

SUMMARY1. A ‘tissue perfusion monitor’ (TPM) to non‐invasively provide an index of skin blood flow (SkBF) has been developed; it employs photoelectric plethysmographic principles to measure changes in the nett flux of red blood cells in superficial microvasculature.2. The ‘tissue perfusion index’ (TPI) varies in proportion to SkBF, provided local haemoglobin concentration does not change significantly. TPI of humans and experimental animals has been shown to indicate reliably, well established phenomena such as decreased SkBF in response to mechanical restriction, cold or Valsalva's manoeuvre, or increased SkBF in response to heat, acetylcholine, sodium nitrite or local nerve blockade.3. SkBF in sheep was varied between 1 and 156 mL/100g per min as measured with radioactive microspheres. Simultaneous measurements were made using the TPM and four laser‐Doppler instruments. The TPI yielded a correlation coefficient of 0.938, and when data were expressed as percentage change, the regression line did not differ significantly from the line of identity and the root‐mean‐square‐error was 6.2%. Data for the laser‐Doppler indices of SkBF were, respectively, 0.549–0.786, highly significant deviations in slopes, and 13.6–16.7%.4. Thus, the TPI is a reliable index of changes in SkBF. Compared with some other available instruments, the TPM is more precise; it is also less sensitive to movement artefact, can be completely portable by battery operation, probes can be multiplexed to a single meter and it is likely to be much less expensive than current lasers.5. Applications include, for example, experimental investigations of SkBF in man and animals, clinical uses such as evaluation of the efficacy of regional nerve blockade or of circulatory restitution after reconstructive surgery, and clinical tests of neuro vascular function.
ONCOGENES: PAST, PRESENT AND FUTURE
Authors: Klinken S. Peter 
Published: June 2007

SUMMARY1. Certain retroviruses contain specific genes (oncogenes) which induce tumours.2. These viral genes were shown to have normal counterparts in the mammalian genome which were termed proto‐oncogenes or cellular oncogenes.3. This breakthrough provided a molecular explanation for tumour formation; viz. cells become transformed when regulation of cellular oncogenes goes awry.4. Evidence for aberrant control of proto‐oncogenes in human malignancies was obtained when chromosomal translocations in Burkitt's lymphomas and chronic myelogenous leukaemia localized to the myc and abl cellular oncogenes, respectively.5. Recent studies have demonstrated that proto‐oncogenes govern cellular proliferation and can be from any part of the signal transduction pathway, for example, growth factors, receptors, intracellular second messengers or nuclear transcription regulators.
EFFECT OF MINERALOCORTICOIDS AND SALT LOADING ON RENIN RELEASE, RENAL RENIN CONTENT AND RENAL RENIN mRNA IN MICE
Authors: Barrett G. , Morgan T. , Smith M. , Aldred P. 
Published: June 2007

SUMMARY1. DOCA and 9α‐fludrocortisone were given to mice on a high‐sodium diet for periods of up to 20 weeks, resulting in decreases in plasma renin concentration, renal renin concentration and renal renin mRNA with both treatments.2. Plasma renin concentration was suppressed prior to suppression of renin mRNA and renal renin levels, indicating that suppression of synthesis and secretion of renin occur separately.3. The decrease in renal renin concentration that occurred with DOCA was greater and more rapid than the decrease that occurred with 9α‐fludrocortisone, suggesting that DOCA caused intra‐renal breakdown of renin.4. When DOCA was given to mice on a low‐sodium diet, plasma renin concentration and renal renin concentration increased, indicating that the effects of DOCA on renin levels were dependent on dietary sodium.5. Renin secretion and synthesis appeared to be controlled by different mechanisms and sodium balance has an important effect on both processes.