摘要:

SUMMARY1. The effects of quinidine on blood flow rate and developed tension were studied in isolated, blood‐perfused papillary muscle preparations of the dog. Drugs were injected into the anterior septal artery.2. Quinidine caused a dose‐related increase in blood flow rate; the mean dose producing a 100% increase in blood flow rate was about 0·3 mg.3. Quinidine in doses of 0·01–0·1 mg produced a positive inotropic response. With 0·3–1 mg of quinidine the positive inotropic response was preceded by a transient negative inotropic response. With 3 mg there was a monophasic negative inotropic response, the developed tension being reduced by about 40% of control.4. Propranolol had no statistically significant effects on the responses of the blood flow rate and developed tension caused by quinidine.5. These results indicate that quinidine has an action on coronary vessels in lower doses than on the myocardium, and that in low doses it has a positive inotropic action rather than the well‐known negative inotropic action exerted with

ISSN:0305-1870    

DOI:10.1111/j.1440-1681.1976.tb00586.x

出版商:Blackwell Publishing Ltd    

年代:1976

数据来源: WILEY

摘要:

SUMMARY1. The activity of the enzyme catechol‐O‐methyltransferase (COMT) was determined in the erythrocytes of normal and autistic children.2. There was no difference in enzyme activity between the two groups, although in both the normal and autistic females the erythrocyte COMT activity showed considerable within‐group variation.3. When the erythrocyte homogenates were divided into particulate and soluble fractions, some differences were observed. The COMT activity in the soluble fraction was less in erythrocytes from autistic males than in those from control males, whereas that in autistic females was higher than in those from control fe

ISSN:0305-1870    

DOI:10.1111/j.1440-1681.1976.tb00587.x

出版商:Blackwell Publishing Ltd    

年代:1976

数据来源: WILEY

摘要:

SUMMARY1. The transport of taurocholic acid from portal blood to bile was studied in the anaesthetized rat by injecting a radiolabeled pulse of bile acid.2. The transport process was very rapid, 50% of the dose being secreted within 5 min, and the total dose within 15 min.3. The transport process had a large capacity. The secretory profile was little modified by a 500‐fold increase in the injected dose.4. The transport process was modelled with both analogue and digital computers. The simplest model which fitted the data comprised rapid uptake from portal blood, slow transport across the cell and rapid secretion into bile. The digital computer simulation suggested that this model is not unique, but will require further testin

ISSN:0305-1870    

DOI:10.1111/j.1440-1681.1976.tb00588.x

出版商:Blackwell Publishing Ltd    

年代:1976

数据来源: WILEY

摘要:

SUMMARY1. Glomeruli free from renal tubules and cell debris were isolated in large numbers from rat kidney cortex by a rapid, simple process of graded sieving on stainless steel meshes.2. Glomeruli were viable, had fragments of the arterioles attached and contained renin.3. Glomeruli, when incubated, released renin into the medium. Using a super‐fusion technique this was shown to be time dependent until a basal secretion level was achieved.4. Release of renin was directly proportional to the number of glomeruli and could be stimulated by isoprenaline, adrenaline and noradrenaline in order of the potency of their action on /?‐adrenoreceptors.5. Isolated glomeruli were therefore established as a useful model system for studying the release of renin by direct influences on the juxtaglomerular cells where haemodynamic, tubular and extrarenal influences are remo

ISSN:0305-1870    

DOI:10.1111/j.1440-1681.1976.tb00589.x

出版商:Blackwell Publishing Ltd    

年代:1976

数据来源: WILEY

摘要:

SUMMARY1. Three resorcinol derivatives with N‐isopropyl (orciprenaline), N‐t‐butyl (terbutaline) and N‐p‐hydroxypheny‐t‐butyl (Me506) amine substituents have been compared with (—)‐isoprenaline for their ability to produce β‐receptor mediated reductions in serotonin‐induced increases in pulmonary resistance, decreases in soleus muscle contractility and increases in heart rate in anaesthetized cats.2. For all parameters studied the four compounds produced similar maximal responses and dose‐response curves were close to parallel. From the graphs doses of the compounds producing 50% of the maximal response (ED50) were interpolated, and from these dose‐ratios with respect to (—)‐isoprenaline [drug ED50: (—)‐isoprenaline ED50] were calculated on a molar basis.3. Increasing the size of the amine substituent from N‐isopropyl to N‐t‐butyl led to an increase in β‐receptor stimulant activity in bronchial and skeletal muscle, but not in the heart. The change from N‐t‐butyl to N‐p‐hydroxyphenyl‐t‐butyl did not further affect stimulant activity in any of the parameters studied.4. Calculation of selectivity ratios [molar dose‐ratio (heart): molar dose‐ratio (pulmonary resistance)] showed that orciprenaline was non‐selective, and that terbutaline and Me506 showed a similar degree of s

ISSN:0305-1870    

DOI:10.1111/j.1440-1681.1976.tb00590.x

出版商:Blackwell Publishing Ltd    

年代:1976

数据来源: WILEY

摘要:

SUMMARY1. The effects of glucagon on the secretion of pancreatic juice were investigated using blood‐perfused canine pancreas preparations.2. Intravenous administration of glucagon (3–30 μg/kg) to the donor dog elicited a dose‐dependent increase in pancreatic secretion. Intra‐arterial administration of glucagon (10–100 μg) into the perfused pancreas also elicited increased secretion.3. There were slight increases in amylase concentration of the pancreatic juice with the largest doses of glucagon given by either route.4. Glucagon‐induced secretion was not modified by treatment with phentolamine, propranolol, atropine, guanethidine, tetrodotoxin, haloperidol, prostaglandin F2a or calcitonin.5. The results suggest that glucagon acts directly on the exocrine cells of the ca

ISSN:0305-1870    

DOI:10.1111/j.1440-1681.1976.tb00591.x

出版商:Blackwell Publishing Ltd    

年代:1976

数据来源: WILEY

摘要:

SUMMARY1. Calcium‐stimulated ATPase activity was studied in a plasma membrane rich fraction of rat pancreas homogenate.2. The enzyme is stimulated to the same maximum rate of ATP hydrolysis by either calcium or magnesium, but the apparent requirement for calcium is five‐fold lower than for magnesium.3. Maximum hydrolytic activity of the enzyme is not increased when additional magnesium is added to the optimal amount of calcium.4. The enzyme does not require Na+or K+for its activation by Ca2+and is not inhibited by ouabain or 2,4‐dinitrophenol.5. Pancreozymin, in concentrations which evoke secretion of zymogen protein, inhibits the calcium‐stimulated ATPase.6. Carbachol and dibutyryl cyclic AMP, in concentrations which increase the release of digestive proteins, do not alter the activity of the calcium‐stimulated enzyme.7. It is suggested that the plasma membrane calcium‐activated enzyme, is not involved in the active calcium extrusion, previously reported to occur with use of the various pancreatic secretago

ISSN:0305-1870    

DOI:10.1111/j.1440-1681.1976.tb00592.x

出版商:Blackwell Publishing Ltd    

年代:1976

数据来源: WILEY

摘要:

SUMMARY1. Isolated rat kidneys were perfused at a constant pressure of 90 mmHg in a single‐pass system with either a cell‐free medium or a suspension of washed bovine red blood cells, free of the components of the renin‐angiotensin system. In red blood cell perfused kidneys renal haemodynamics and sodium reabsorption corresponded closer to values observed in the intact rat than in cell‐free perfused kidneys.2. In red blood cell‐perfused kidneys in the absence of plasma renin substrate autoregulation of renal blood flow was almost complete at pressures above 90 mmHg, provided that perfusion pressure was changed rapidly.3. Renin release varied inversely with perfusion pressure within a pressure range from 50 to 150 mmHg; the greatest changes of renin release occurred, when perfusion pressure was reduced from 90 to 70 mmHg; maximal stimulation of renin release was observed at 50 mmHg. After reduction of perfusion pressure, renin release immediately started to rise and reached a new level within 5 min. Local reduction of perfusion pressure in small arteries and arterioles by the injection of microspheres induced a short‐lasting decrease in renal plasma flow and a transient stimulation of renin release.4. High concentrations of furosemide stimulated renin release by a direct intrarenal mechanism.5. Isoproterenol stimulated renin release in low concentrations without a concomitant vasodilation, whereas high concentrations induced an increase in both renal plasma flow and renin release. The effects of isoproterenol were completely blocked by propranolol.6. Sodium nitroprusside induced similar increases in renal plasma flow, as did high concentrations of isoproterenol, but only a small and slow increase in renin release was observed.7. Angiotensin II (AII) suppressed renin release in concentrations corresponding to plasma levels measured in the intact rat independently of its vasoconstrictor effects, whereas vasopressin in antidiuretic concentrations did not affect renin release.8. AII, AI, synthetic tetradecapeptide renin substrate (TDP), crude and purified rat plasma renin substrate induced a dose‐dependent reduction in renal plasma flow. SQ 20 881, a competitive inhibitor of converting enzyme, and low doses of l‐Sar‐8‐Ala‐AH (saralasin), a competitive antagonist of AH, did not change renal plasma flow, whereas high concentrations of saralasin had a vasoconstrictor effect on their own.9. Saralasin inhibited the vasoconstrictor effects of All and TDP to a similar degree. SQ 20 881 inhibited the vasoconstrictor effects of AI and purified renin substrate, but did not influence the actions of TDP and the crude renin substrate preparation.10. From these data it is concluded, that AI is converted into AH within the kidney at a rate of 1–2%. The vasoconstriction induced by the crude renin sub‐strate probably does not involve the All receptors. TDP may act by itself on the AII receptors or via the direct intrarenal formation of AII. The vasoconstriction induced by purified renin substrate is probably due to the intrarenal formation of AI and its sub

ISSN:0305-1870    

DOI:10.1111/j.1440-1681.1976.tb00593.x

出版商:Blackwell Publishing Ltd    

年代:1976

数据来源: WILEY

摘要:

SUMMARY1. Conscious rats which had undergone unilateral renal artery constriction were infused for 1 h with a specific antagonist of angiotensin II, 1‐Sar‐8‐Ala‐angiotensin II (P‐113).2. There was a highly significant correlation between the change in blood pressure induced by P‐113 and the pre‐infusion plasma renin concentration (PRC), regardless of initial blood pressure or the duration of stenosis. However, the blood pressure fall was not significantly greater in nineteen hypertensive rats than in eleven which remained normotensive. P‐113 did not abolish the hypertension.3. The extent to which angiotensin II supports blood pressure in rats with renal artery constriction is directly rel

ISSN:0305-1870    

DOI:10.1111/j.1440-1681.1976.tb00594.x

出版商:Blackwell Publishing Ltd    

年代:1976

数据来源: WILEY

摘要:

SUMMARY1. The metabolic fate of the insoluble bile acid sequestrant polidexide, (poly‐[2‐(diethylamino)ethyl] polyglycerylenedextran hydrochloride), was studied in four adult humans following the oral administration of the14C‐labelled substance.2. The mean cumulative recovery of14C in faeces was 95·3% (s.e.m. = 1·1) of the administered dose, while mean cumulative recovery in urine was 0·37% (s.e.m. = 0·13) of the oral dose.3. Only background levels of radioactivity were detectable in plasma samples taken 1·3 days after administration of tracer.4. The findings suggested that polidexide was not absorbed from the gastrointestinal tract in man to any signific

ISSN:0305-1870    

DOI:10.1111/j.1440-1681.1976.tb00595.x

出版商:Blackwell Publishing Ltd    

年代:1976

数据来源: WILEY