摘要:

SUMMARY1.In vivomicropuncture techniques, with and without peritubular capillary perfusion, were used to study the effects of high extracellular Na and Cl concentrations on transepithelial volume (Jv) and sodium (JNa) fluxes in rat proximal tubules.2. In a double blind manner, the shrinking drop technique of Gertz was used to measure Jv; JNawas calculated from this and the tubular fluid Na concentration.3. At both 184 and 279 mmol/l pericellular Na concentrations (both inside and outside the tubular epithelium), net Jvdecreased significantly by 15 and 64%, respectively. Net JNaremained constant at 184 but decreased by 29% at 279 mmol/l Na concentration.4. Thus, at both Na concentrations, when translated to free flow conditions, fractional Na reabsorption must have decreased. These findings, also supported by previous results at these Na concentrations, indicate that active Na transport was inhibited by high pericellular Na concentrations.5. When intratubular Cl concentration was varied between 108 and 138 mmol/l while peritubular Cl was maintained constant (blood perfusing the capillaries), neither Jvnor JNachanged. Thus, at zero tubular flow, differential Cl/HCO3concentrations do not provide significant driving forces for net Jvor JNa.6. When only intratubular but not peritubular Na was elevated to 279 mmol/l, Jvand JNaincreased markedly by 50 and 187%, providing evidence that a true solvent drag (solute drag) effect does exist in rat proximal tubules.7. These findings offer a mechanism to explain why Na reabsorption is not increased when the filtered load of Na is increased with an elevation of plasma Na. That is, the high Na, which surrounds the tubular epithelium, inhibits Na and volume flux at the cellular level by mechanisms as yet unknown. The results also showed that differential Cl/HCO3concentrations made no difference to Na or volume fluxes at zero tubular flow.

ISSN:0305-1870    

DOI:10.1111/j.1440-1681.1987.tb01893.x

出版商:Blackwell Publishing Ltd    

年代:1987

数据来源: WILEY

摘要:

SUMMARY1. Changes in plasma atrial natriuretic peptide (ANP) were examined in conscious rabbits in response to a 33% blood volume expansion in intact animals and after blockade of cardiac nerve activity.2. Blood volume expansion by one‐third markedly increased right atrial pressure and resulted in a four‐fold increase in plasma ANP.3. Cardiac nerve blockade with intrapericardial procaine had no effect on resting plasma ANP levels. The ANP responses to volume expansion in the presence of cardiac nerve blockade were similar to those seen in intact animals.4. Release of ANP from its cardiac stores in response to volume expansion is not influenced by cardiac nerve activ

ISSN:0305-1870    

DOI:10.1111/j.1440-1681.1987.tb01894.x

出版商:Blackwell Publishing Ltd    

年代:1987

数据来源: WILEY

摘要:

SUMMARY1. The effects of neuropeptide Y (NPY) on the pressor responses to intravenous injections of phenylephrine and to reflex activation of the sympathetic nervous system by stimulation of the sciatic nerve were examined in anaesthetized rats.2. NPY (10–20 μg/kg) always potentiated the pressor response to exogenous phenylephrine (by a mean of 28.1 ± 5.0%). The effect of the same dose of NPY on the pressor response to sciatic nerve stimulation was variable (sometimes inhibition, sometimes potentiation).3. NPY appears to act by potentiating post‐synaptic a‐adrenoceptor‐mediated vasoconstrictor effects. It may also inhibit noradrenaline release by a presynaptic action. Thus the net effect of NPY on sympathetic activationin vivomay depend on the balance between these two opposin

ISSN:0305-1870    

DOI:10.1111/j.1440-1681.1987.tb01895.x

出版商:Blackwell Publishing Ltd    

年代:1987

数据来源: WILEY

摘要:

SUMMARY1. (—)[125I]‐Cyanopindolol (CYP) binding to non‐β‐adrenoceptor sites in dog kidney was characterized in homogenate preparations and their distribution in sections determined using autoradiography.2. In homogenate studies, (—)[125I]‐CYP bound to a single population of non‐interacting sites (Bmax= 5.45, s.e.m. = 1.00 fmol/mg wet weight; nH = 0.99, s.e.m. = 0.01) with high affinity (KD= 3.84, s.e.m. = 0.76 nmol/l,n= 4).3. In competition studies, compounds selective for α‐ and β‐adrenoceptors, muscarinic cholinoceptors and receptors for 5‐HT, histamine and benzodiazepines, calcium channel antagonists, catecholamine uptake inhibitors, MAO inhibitors and adrenergic neurone blockers were ineffective at concentrations of 10 μmol/l.4. Compounds selective for dopamine D1‐receptors (fluphenazine, SCH 23390 and SK&F 82526) and D2‐receptors (pimozide, domperidone, spiperone, haloperidol, sulpiride, cis‐ and trans‐flupenthixol) competed with similar affinities (5–25 μmol/l) for (—)[125I]‐CYP binding.5. In autoradiographic studies, (—) [125I]‐CYP binding to non‐β‐adrenoceptor sites was localized over glomeruli, juxtaglomerular apparatus, distal tubules, blood vessels and medullary rays and tubules.6. It is concluded that in dog kidney, (—)[125I]‐CYP binds t

ISSN:0305-1870    

DOI:10.1111/j.1440-1681.1987.tb01896.x

出版商:Blackwell Publishing Ltd    

年代:1987

数据来源: WILEY

摘要:

SUMMARY1. The effect of the opioid peptides [Met5]enkephalin‐Arg6‐Phe7(MEAP) and [Met5]enkephalin‐Arg6‐Gly7‐Leu8(MEAGL) were compared with those of [Leu5]enkephalin and [d‐Ala2, Met5]enkephalinamide (DAME) on cholinergic neuro‐transmission in the rabbit isolated atria.2. Rabbit isolated atria had a resting rate of 190 beats/min. In the presence of the β‐adrenoceptor antagonist propranolol (0.3 μmol/l), atria responded to electrical field stimulation with a cholinergically mediated negative chronotropic response. The opioid peptides had no effect on the resting rate, but inhibited the negative chronotropic response to field stimulation. The IC50values for inhibiting the cholinergic responses were 1.4 μmol/l for [Leu5]enkephalin (LE), 1.4 μmol/l for MEAP, 1.3 μmol/l for MEAGL and 0.2 μmol/l for DAME. Responses of a similar magnitude to exogenous acetylcholine were unaffected.3. Thus, MEAP, MEAGL and LE had similar potencies but DAME was about seven times more potent in inhibiting cholinergic neurotransmission in the rabbit isolated atria. The site of inhibition appear

ISSN:0305-1870    

DOI:10.1111/j.1440-1681.1987.tb01897.x

出版商:Blackwell Publishing Ltd    

年代:1987

数据来源: WILEY

摘要:

SUMMARY1. Salivary paracetamol elimination was studied in nine patients with congestive cardiac failure (CCF). Six healthy volunteers served as the control group.2. Paracetamol eliminationt1/2and apparent volume of distribution were significantly higher in patients with CCF compared with controls. There was no significant change in the clearance rate.3. Drug therapy of failure for a period of 15 days returned thet1/2and V values to normality.

ISSN:0305-1870    

DOI:10.1111/j.1440-1681.1987.tb01898.x

出版商:Blackwell Publishing Ltd    

年代:1987

数据来源: WILEY

摘要:

SUMMARY1. Little information exists on the quantitation of mucus barrier and its vagal control; hence, the effect of vagotomy on the two components of the mucus barrier was studied in the glandular regions of rat stomach.2. Bilateral subdiaphragmatic vagotomy was carried out by cutting both vagus nerves at the level of the lower end of the oesophagus. After 14 days, the glycoproteins in mucosal epithelial cells were identified by periodic acid Schiff's (PAS) staining technique and were assessed by calculating the ratio of the mucosal height to that of the thickness of PAS‐positive materials in it. The adherent mucus was estimated by the Alcian blue binding technique and the results were compared with control animals subjected to mock vagotomy.3. The bilateral subdiaphragmatic vagotomy caused a significant reduction in mucosal epithelial PAS‐stainable materials content in oxyntic and pyloric gland areas.4. The operation also caused a decrease in Alcian blue binding capacity of both the glandular regions.5. The data suggest that the absence of vagal influence causes weakening of both the lines of mucus barrier. The findings support the hypothesis that the vagal system must be intact in the rat in order to maintain gastric mucus glycoproteins and thereby mucosal integr

ISSN:0305-1870    

DOI:10.1111/j.1440-1681.1987.tb01899.x

出版商:Blackwell Publishing Ltd    

年代:1987

数据来源: WILEY

摘要:

Book reviews in this article:Bronchial Hypetresponsivcncss: Normal and Abnormal Control, Assessment and Therapy.Edited by J. A. Nadel, R. Pauwels and P. D. Snashall. Pages xiv + 425. Illustrated. Blackwell Scientific Publications, Oxford. 1987. £49.50.Selenium in Biology and Medicine. Proceedings of the Third International Symposium in Beijing, People's Republic of China. Parts A and B.Edited by Gerald F. Combs, Jr, Julian E. Spallholz, Orville A. Levander and James E. Oldfield. Pages: Part A xv + 555, Part B xxiv + 583. Illustrated. Van Nostrand Reinhold Co., New Yor

ISSN:0305-1870    

DOI:10.1111/j.1440-1681.1987.tb01900.x

出版商:Blackwell Publishing Ltd    

年代:1987

数据来源: WILEY