摘要:

AbstractHenle's loops of surface nephrons in rat kidneys were perfused orthogradely with various solutions of different compositions, while the stop‐flow pressure (SFP) was monitored in the early proximal tubulus as a measure of the tubuloglomerular feedback response. Modified Ringer solution or iso‐osmotic solutions of NaCl, KC1, LiCl, RbCl, choline‐Cl, and Na‐acetate used to perfuse Henle's loop led to significant SFP decrease indicating an intact operation of a tubuloglomerular feedback mechanism. Increased rates with isoosmotic solutions of sodium sulphate, potassium sulphate and mannitol did not yield SFP alterations. In order to estimate intratubular sodium and chloride concentration at the macula densa during Ringer‐, LiCl‐, choline‐Cl‐, and Na‐acetate perfusion, early distal tubular fluids were collected at low and high perfusion rates, corresponding to an absent or a maximal feedback response. Analysis was performed by microflame photometry and microchloride titration. The results showed that there does not exist a common threshold for the early distal sodium or chloride concentration at which the feedback starts to operate. We conclude that the intraluminal signal at the macula densa, initiating a tubuloglomerular feedback response is not necessarily coupled to a single ion species. Either an unspecific ion transfer or more passive events of ionic interaction with the macula densa cells might operate as the initiating step in

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1978.tb06228.x

出版商:Blackwell Publishing Ltd    

年代:1978

数据来源: WILEY

摘要:

AbstractThe electrochemical forces for chloride transport in the proximal tubule of the rat kidney were studied using micropuncture techniques. Electrical transmembrane potentials were recorded in randomly punctured tubules with Ling‐Gerhard electrodes. Chloride activities in the luminal, cellular and interstitial compartments were measured with ion selective micro‐electrodes. Electrical potential measurements between cell to interstitium and lumen to interstitium were ‐72.1 ± 2.6 mVand ± 0.5±1.4mV(mean ± S.D.)respectively. The calculated chloride concentrations for lumen, cell and interstitium were 133.0±10.3 mM, 8.5±1.0 mM and 99.1 ± 3.2 mM (mean ± S.D.) respectively. The net electrochemical forces, qualitatively, offer a passive chloride ion pathway through the tubular wall and a chloride equilibrium over the luminal membrane s

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1978.tb06229.x

出版商:Blackwell Publishing Ltd    

年代:1978

数据来源: WILEY

摘要:

AbstractBlood velocities in 12 arteries were recorded by an ultrasonic doppler flowmeter in 11 young adults. Two major types of velocity patterns existed at rest. In certain arteries (the common carotid, the external carotid, the superficial temporal and the proper palmar digital arteries) flow was towards the periphery throughout the entire pulse cycle. Other arteries (the common femoral, the popliteal, the posterior tibial and the pedal artery) exhibited retrograde flow in part of the pulse cycle. In each individual a spontaneous variation between these two velocity patterns was observed in the subclavian, the axillary, the brachial and the radial artery. The velocity pattern of each artery is described, and absolute blood velocities at recognizable instances during the pulse cycle are given. The influence of peripheral resistance on the velocity pattern was investigated by reactive hyperaemia of the femoral artery. We find that not only is there an upward displacement of the resting femoral curve relative to the line of zero, but the shape of the velocity pattern is also changed. Our conclusion is that peripheral resistance is of major importance not only for the mean velocity, but also for the shape of the velocity pattern in the artery.

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1978.tb06230.x

出版商:Blackwell Publishing Ltd    

年代:1978

数据来源: WILEY

摘要:

AbstractFluxes of45Ca2+were studied in β‐cell rich islets of non‐inbredob/ob‐mice, using LaCl3to wash out extracellular and superficially bound45Ca2+. The ionophore A‐23187 (10,μM) increased the45Ca2+uptake in islets both at 3 and 20 mM D‐glucose, the effect being more pronounced after 10 min than after 120 min of incubation. In incubations for 120 min, 20 mM D‐glucose induced a higher uptake of45Ca2+than did A‐23187. The ionophore enhanced the unidirectional efflux of45Caa+from preloaded islets. Pretreatment of islets with 20 mM D‐glucose in non‐radioactive medium inhibited the subsequent D‐glucose‐induced45Ca2+uptake. Similar pretreatment with A‐23187 increased the subsequent ionophore‐induced45Ca2+uptake. The results suggest that A‐23187 acts by catalyzing Ca2+fluxes across the β‐cell plasma membrane. The different effects of D‐glucose and A‐23187 on45Ca2+fluxes suggest that the two agents act through

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1978.tb06231.x

出版商:Blackwell Publishing Ltd    

年代:1978

数据来源: WILEY

摘要:

AbstractKallikrein was located by the direct immunofluorescence technique to the granule‐containing luminal portion of pancreatic acinar cells. For the demonstration of the intracellular distribution of pancreas kallikrein,in vivofixation of the gland was necessary. No kallikrein was found in the duct cells or in the islets of Langerhans. Quantitation by single radial immunodiffusion showed that the concentration of kallikrein in the pancreas was 132 ± 51 μg/g wet weight,i.e.1/91 that of the rat submandibular gland. Bz‐Arg‐OEt‐esterases were in |the pancreas found as pro‐enzyme but as active enzyme in the submandibular gland. Trypsin‐like esterases, hydrolyzing σ‐amino caproic acid naphtol‐AS‐D‐ HBr (ACA), were found in the active form in both submandibular gland and pancreatic homogenates. The submandibular gland contained per g wet weight 6 times as much ACA‐esterase activity as the pancreas. In the submandibular gland, kallikrein and ACA‐esterase activity were found together in practically all granular tubular cells. Thus, the granular tubular cell contains kallikrein as well as other trypsin‐like enzymes like the ACA‐esterase, and is in this way comparable to the pancreatic acinar cell. An extraglandular function of kallikrein is suggested for the pancreas in contrast to other kallikr

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1978.tb06232.x

出版商:Blackwell Publishing Ltd    

年代:1978

数据来源: WILEY

摘要:

AbstractSympathetic chain ganglia of 3‐day‐old rats were cultured in Rose chambers for 5 days. Each chamber contained either two ganglia or a ganglion and a piece of heart atrium. Visual examination failed to show an increased density or length of nerve fibers growing towards the other explant. However, actual measurements showed that the length of nerve fiber outgrowth towards the atrium explant was about 10% longer than the mean outgrowth to all directions, the difference being statistically significant (P<0.0001). In ganglion‐ganglion pair cultures the nerve fiber outgrowth towards the other ganglion tended to be shorter than that to other directions. It is tentatively concluded that atrium explants exert a growth‐promoting influence on sympathetic nerve fibers in cultures, possibly due to diffusion of a growth‐promoting substance from the atriu

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1978.tb06233.x

出版商:Blackwell Publishing Ltd    

年代:1978

数据来源: WILEY

摘要:

AbstractThe Sperber technique in the hen is particularly suitable for the study of renal tubular secretion. However, results obtained with this technique vary considerably, due to an unpredictable and highly variable shunting of renal portal blood. In an attempt to get a total and stable renal perfusion by portal blood from the leg, appropriate shunt vessels were ligated. This procedure was found to force all portal blood from the leg to perfuse the ligated kidney, without affecting the symmetry of glomerular filtration or renal clearance of 125‐I‐Na‐o‐iodohippurate between the kidneys. In conclusion, the abolition of renal portal shunt flow allows use of the Sperber technique for a direct estimation of the true tubular excretion fraction (TTEF) of a substance. Thus, TTEFPAH, a measure of the tubular excretion efficiency of para‐amino‐hippuric acid, was found to be about 70%. The stable renal perfusion in ligated animals will also facilitate comparative studies of renal tubular excretion in the hen. Moreover, no animal has to be rejected due to a low renal perfusion of portal blood. Furthermore, the use of ligated hens makes it unnecessary to use markers for the renal perfusion of portal blood when steady‐state experiments are performed. Finally, the total renal perfusion of portal blood in ligated animals will facilitate the demonstration of a secretory component in the renal handling of substances with a low affinity for the renal tra

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1978.tb06234.x

出版商:Blackwell Publishing Ltd    

年代:1978

数据来源: WILEY

摘要:

AbstractThe lactate concentration in different muscle fibre types was determined in biopsy specimens from human vastus lateralis muscle after 30 and 60 s of maximal dynamic leg exercise. In addition, muscle fibre type distribution, total lactate dehydrogenase (LDH) activity, and isozymes of LDH were determined. In accordance with previous studies (Thorstensson and Karlsson 1976, Nilssonet al.1977) it was found that an increasing proportion of slow twitch (ST) fibres corresponded to better sustained muscle force. Lactate was found preferentially in fast twitch (FT) fibres after 30 s, but after 60 s this difference was abolished. Differences between the two main muscle fibre types in muscle lactate, total LDH activity, and M‐LDH activity were correlated to muscle fatigue. It was concluded that lactate or associated pH changes primarily in FT fibres could be one factor responsible for the impaired muscle functio

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1978.tb06235.x

出版商:Blackwell Publishing Ltd    

年代:1978

数据来源: WILEY

摘要:

AbstractInhibition of ADH‐secretion and transient water diuresis was observed as acute effects of radio‐frequency lesions in the septal region of goats. The water diuresis was not compensated for by drinking and therefore rapidly induced pronounced hypernatremia and hypovolemia. The development of hypovolemia was accompanied by a rise in plasma renin activity. Lesions of the same kind, but extending into the preoptic region near the medial portion of the supraoptic nuclei induced the inability to excrete excessive water characteristic of SIADH. Determinations of plasma arginine vasopressin suggested that the lesions causing SIADH did not produce any noticeable increase in basic ADH‐secretion. The results suggest that impulses from juxtaventricular receptors regulating ADH‐release and water intake to a considerable extent are transmitted via the septal region, and that elimination of this impulse traffic is sufficient to turn water balance to the negative side. However, reflex volumetric inhibition of the ADH‐secretion does not seem to be mediated by pathways passing through the sept

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1978.tb06236.x

出版商:Blackwell Publishing Ltd    

年代:1978

数据来源: WILEY

摘要:

AbstractThe distensibility of the resistance vessels of skeletal muscle was evaluated in 23 patients with essential arterial hypertension (WSHO grade T‐II), and in 14 normotensive control subjects. Five of the hypertensive patients were well treated for over 2 years and 18 were untreated. The133Xenon wash‐out rate from the anterior tibial muscle during reactive hyperemia was recorded before and during an increase of the vascular transmural pressure, brought about by application of a subatmospheric pressure to the leg. At ambient pressure the133Xenon wash‐out rate did not differ between the normotensive and hypertensive subjects, reflecting equal muscle blood flows. However, when the transmural pressure was augmented the133Xenon wash‐out rate in the normotensive subjects increased about twice as much as in the hypertensive patients. This suggests a decreased distensibility of the resistance vessels in hypertensive patients as compared to normotensive subjects, and supports the concept that structural changes of these vessels take place in arterial hypertension. Since the vascular distensibility was equally reduced in the untreated and well treated hypertensive patients it is indicated that the structural changes in the resistance vessels of the leg muscles do not readily decline during antihypertensive tr

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1978.tb06237.x

出版商:Blackwell Publishing Ltd    

年代:1978

数据来源: WILEY