ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1983.tb07297.x

出版商:Blackwell Publishing Ltd    

年代:1983

数据来源: WILEY

摘要:

Acute renal failure was induced in heparinized rats by clamping the renal artery for 45 min. Ten minutes after recirculation the intrarenal blood flow distribution was measured. For this purpose labelled microspheres were injected together with 86‐Rb chloride. The microspheres were used for determination of cardiac output, total renal and cortical blood flow, and 86‐Rb for calculations of medullary blood flow. Total renal blood flow was reduced from 7.6 to 3.8 mlmin‐1· g‐1and cortical blood flow was reduced from 11.7 to 7.0 ml · min‐1· g‐1. In the outer stripe of the medulla there was a reduction from 2.5 to 1.4 ml · min‐1· g‐1. In the inner stripe there was a more pronounced reduction from 1.8 to 0.2 ml · min‐1· g‐1and in the inner zone from 0.8 to 0.1 ml · min‐1· g‐1. The marked reduction in the blood flow to the renal medulla after recirculation is suggestive for a medullary ischemia, which might be responsible for the characteristic dys

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1983.tb07234.x

出版商:Blackwell Publishing Ltd    

年代:1983

数据来源: WILEY

摘要:

The human threshold of sensation of 50 Hz current has hitherto been considered to be around 1 mA. A new sensing mechanism is reported which lowers the threshold about 3 decades. It is elicited when the skin slides on the current carrying conductor, and the sensation disappears when the skin is wet. The sensation is a feeling of vibration or increased surface roughness. The sensing mechanism has been shown to be due to electrostatic forces in the skin caused by the electric field in a poorly conducting stratum corneum. The mechanism is primarily potential dependent, and the absolute threshold of sensation has been found to be about 1.5 volt or 0.15 μA rms at 50 Hz. In practical daily‐life situations it is shown that 82% of 40 test subjects were able to sense a current of 2 μA rms, 50

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1983.tb07235.x

出版商:Blackwell Publishing Ltd    

年代:1983

数据来源: WILEY

摘要:

Chronic i. p. treatment with 1‐dopa‐carbidopa for 3 weeks in hemitransected male rats leads on one hand to tolerance to l‐dopa induced turning behaviour and on the other hand to behavioural and biochemical signs of dopamine (DA) receptor supersensitivity on the intact side. Thus, the apomorphine induced ipsilateral turning behaviour is enhanced and the Kdvalues of the3H‐spiperone binding sites linked to DA receptors of the D2type on the intact, but not on the denervated side are reduced by 40%. However, the number of3H‐spiperone binding sites is reduced by 20% in striatal membranes on the intact side after this type of treatment. Therefore, chronic treatment with a catecholamine (CA) precursor leads to selective adaptive changes at intact striatal DA synapses with certain signs of the expected development of DA receptor subsensitivity, but above all with signs of paradoxical development of DA receptor supersensitivity. A hypothesis is introduced to explain thes

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1983.tb07236.x

出版商:Blackwell Publishing Ltd    

年代:1983

数据来源: WILEY

摘要:

The present findings show that nicotine given i. v. can within minutes induce increases of ACTH, vasopressin and prolactin secretion in the male rat, giving further evidence for the existence of nicotine‐like cholinergic receptors involved in the regulation of these hormones. These changes were associated with rapid reductions of NA levels in the subependymal layer of the median eminence, in the nuc dorsomedialis hypothalami and in the anterior and posterior periventricular hypothalamic area as revealed by quantitative micro‐fluorimetrical measurements of CA fluorescence. Intraindividual correlations indicate the involvement of an inhibitory noradrenergic mechanism in the subependymal layer of the median eminence in the regulation of ACTH secretion, the involvement of noradrenergic mechanisms in the posterior periventricular area in the regulation of prolactin secretion and the involvement of dopaminergic mechanisms in the medial palisade zone of the median eminence in the regulation of prolactin secretion. A rapid rise of prolactin secretion seems to be associated mainly with a reduction of NA levels in the posterior periventricular area indicating the existence of a possible facilitatory noradrenergic mechanism in this region regulating prolactin secret

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1983.tb07237.x

出版商:Blackwell Publishing Ltd    

年代:1983

数据来源: WILEY

摘要:

Portal veins were subjected to stretch and shortening at rates varying from 0.2 to 47% of initial muscle length/s. The total length change was 33% of initial length which was about 6 mm at the resting preload of 1 mN. Relaxed portal veins (Ca‐free medium) gave curvilinear stress‐strain relations which were practically independent of the rate of the length change and they were similar in their ascending and descending branches (non‐linear parallel elasticity). In contractures produced by K+ or hyperosmolar solution the stress‐strain curves showed pronounced and rate dependent hysteresis. The stretch response in K+ contracture showed initially a steep increase in force in relation to rate of lengthening (dP/dL) up to an apparent break‐point at 2–3% elongation, after which the rise in force was quite independent of the rate of stretch. The break‐point is blunted and shifted to greater length change in portal vein due to large series compliance, but in analogy with interpretations from other types of muscle it may reflect the limit of deformation of attached cross bridges. In hypertonicity contracture dP/dL increased in proportion to rate of stretch. Earlier isotonic quick release experiments showed that the force‐velocity relation of portal vein smooth muscle is markedly different in K+ and hyperosmolality contractures, respectively. Similar differences were found when force‐velocity relations were constructed from the present experiments by plotting active force versus rate of imposed length changes. This indicates that the viscous properties of contracted blood vessels, as revealed in stress‐strain hysteresis, are greatly determined by the force‐velocity characteristics of the smooth muscle actomyosin system. There are, however, certain differences between the force‐velocity curves from isotonic quick release experiments and from the present isovelocity study which

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1983.tb07238.x

出版商:Blackwell Publishing Ltd    

年代:1983

数据来源: WILEY

摘要:

Efflux of preloaded [3H]tryptophan from rat cerebral cortex slices has been monitored into superfusion media that were altered in their sodium content. Total replacement of sodium with choline greatly increased the release of tryptophan. This release could be cancelled by re‐introducing sodium into the slices. A brief exposure to ouabain, an efficient inhibitor of Na+, K+‐ATPase activity, only slightly increased tryptophan efflux at the concentration of 0.1 mM, whereas at 1.0 mM it produced a similar effect as the sodium‐free medium. Accordingly, when the slices were superfused in the presence of ouabain and sodium, the change of medium to sodium‐free caused much greater relative enhancement of tryptophan efflux with 0.1 than 1.0 mM ouabain. Tryptophan efflux was modified by changes in sodium fluxes also in slices initially depleted of sodium ions and treated with ouabain. The results suggest that the sodium‐free medium and ouabain have a similar mechanism of action in modifying the tryptophan transport, and that the cation gradients across the cell membranes are more crucial for normal amino acid transport than the functional Na+,

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1983.tb07239.x

出版商:Blackwell Publishing Ltd    

年代:1983

数据来源: WILEY

摘要:

The transport of hypotaurine, the precursor of the probable neuromodulator taurine, was investigated using mouse brain synaptosomal preparations. Hypotaurine uptake was concentrative, energy‐and sodium‐dependent and strongly inhibited by GABA,l‐DABA (l‐2,4‐diaminobutyric acid) and β‐alanine, suggesting interactions with GABA uptake systems. The uptake consisted of only one saturable transport component both in adult and in 6‐day‐old brain, being more efficie

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1983.tb07240.x

出版商:Blackwell Publishing Ltd    

年代:1983

数据来源: WILEY

摘要:

Renal vascular beds from spontaneously hypertensive rats (SHR) at different stages of hypertension, from two‐kidney, one‐clip renal hypertensive rats (RHR) and from uninephrectomized rats (UNR) were in constant‐flow, paired perfusions compared with kidneys from normotensive control rats (NCR) concerning vascular smooth muscle sensitivity to noradrenaline (NA) and resistance vessel reactivity, as reflected by the position, respectively the shape, of the dose‐resistance response curves. None of these kidney variants differed significantly from controls concerning smooth muscle sensitivity to NA during in vitro perfusion. However, both the steepness and maximal pressor responses of the renal resistance curves increased progressively with age in SHR, to become ultimately much enhanced when related to age‐matched controls. It suggests a well preserved smooth muscle contractility and a progressive elevation of the average wall/lumen ratio in the SHR renal resistance vessels. Also the untouched, “high‐pressure” RHR kidneys showed increased vascular reactivity, while it was somewhat reduced in the clipped, “low‐pressure” RHR kidneys and unchanged in the hypertrophied but normotensive UNR kidneys. These results, when combined with other finings concerning renal vascular design (Göthberg&Folkow 1982a), illustrate how the renal resistance vessels readily adapt structurally to hypertension, hypotension, kidney hypertrophy and also with age, and in directions which tend to chronically “autoregulate” glomerular b

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1983.tb07241.x

出版商:Blackwell Publishing Ltd    

年代:1983

数据来源: WILEY

摘要:

The effect of ischemia on the hepatic cell membrane potential (MP) was studied in vivo in fed and fasted rats. Liver ischemia was induced for 1 h by clamping all afferent vessels to the left lateral and medial lobes and was followed by a 3 h period of reflow. The liver content of ATP, glucose, lactate and glycogen was repeatedly measured and related to the MP changes. The initial ATP content was 40% higher and the glycogen content 10 times higher in the fed animals, while the MP was similar in both groups. During the ischemic period the ATP content as well as the MP decreased in a similar manner in both groups of animals. During reflow the ATP content increased to about 50% of the initial value in both groups of animals. The MP was normalized more rapidly in fed animals than in fasted ones, indicating a better capability for recovery after ischemic injury in fed animals.

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1983.tb07242.x

出版商:Blackwell Publishing Ltd    

年代:1983

数据来源: WILEY