摘要:

Peripheral nerves of the cat such as the vagal and the sciatic nerves have been shown to contain a peptide with insulin‐like properties. The aim of the present study was to investigate whether insulin‐like immunoreactivity (ILI) can be demonstrated in human nervous tissue collected from autopsy material. Biopsies were taken in connection with autopsy from various peripheral nerves and their content of ILI was investigated. ILI in amounts up to about 12 ng g‐1was found in about 30% of all biopsies taken from peripheral nerves. The ILI coeluted with a bovine insulin standard in an HPLC system indicating that it corresponds to a peptide identical with or similar to pancreatic insulin. Autopsy specimens taken from the sciatic nerve of individuals with diabetes type II or from individuals without established diabetes contained similar amounts o

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1988.tb08391.x

出版商:Blackwell Publishing Ltd    

年代:1988

数据来源: WILEY

摘要:

The present study examines analgesic properties of 2 Hz peripheral nerve stimulation in four different tests of nociception: the tail‐flick, hot‐plate, jump‐response and formalin tests. Radial, sciatic and trigeminal nerve stimulation produced decreased response amplitudes to weak electrical foot shocks in the jump‐response test. The fact that all three nerves produced the same effect suggests the involvement of general, non‐segmental mechanisms. The nerve stimulation produced a characteristic after‐effect, lasting several minutes, suggesting the involvement of supraspinal mechanisms. The radial nerve stimulation resulted in the most pronounced reduction in jump responses. Sciatic nerve stimulation also produced analgesia in the formalin test but had no effect on the responsiveness to a brief stimulus at threshold level in the hot‐plate or the tail‐flick tests. It is concluded that analgesia by peripheral nerve stimulation in animals is most readily detected by tests allowing a quantitative evaluation of responses to above‐threshold noxious stimuli and not only measuring reactions occurring at the threshol

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1988.tb08392.x

出版商:Blackwell Publishing Ltd    

年代:1988

数据来源: WILEY

摘要:

A rectangular pseudomesothelial‐lined chamber was used to elucidate the hypothesis that in adult rats neurotrophic factors are formed after nerve injury and may influence regeneration of peripheral nerves. The proximal end of a cut sciatic nerve was inserted into one corner of the chamber. In one group of animals the distal end of the cut sciatic nerve was implanted in the diagonally opposite corner of the chamber. In another group we just introduced the proximal end of the sciatic nerve; no distal implant was used. The organization, length and direction of the nerve fibres, regenerating from the proximal end of the sciatic nerve, was visualized immunohistochemically with the aid of antibodies against neurofilaments at 2, 3 and 4 weeks after surgery. When a distal sciatic nerve segment was used, nerve fibres regenerating from the proximal cut end of the sciatic nerve showed an organized growth across the chamber, formed bundles and grew into the diagonally implanted nerve piece. If there was no distal implant, the growth of the randomly directed nerve fibres ceased after about two weeks, resulting in formation of a neuroma‐like structure. Increased immunoreactivity of the trophic peptide insulin‐like growth factor I (IGF‐I, somatomedin C) was demonstrated in the regenerating nerve, most evidently in reactive Schwann cells.It is concluded that a positive neurotropic effect is exerted on growing nerve fibres by injured, reactive peripheral nerve tissue. There could tentatively be a relation between nerve regeneration and local formation of trophic

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1988.tb08393.x

出版商:Blackwell Publishing Ltd    

年代:1988

数据来源: WILEY

摘要:

A method to measure time‐dependent volume changes in macula densa (MD) cells is described. Cell volume is calculated from cell height measurements for which an image‐splitting eyepiece is used. This paper presents the results of experiments designed to investigate the behaviour of the macula densa cells in anisosmotic media, to evaluate the cell volume response to sudden decreases in luminal or peritubular osmolarity and to examine the effect of different luminal NaCl concentrations on the steady‐state isosmotic cell volume and on the regulatory volume response to anisosmotic media. The result showed that induced alteration in macula densa cell volume did not change macula densa surface area, but only cell height. The mean control cell height was 13.3 μm ± 0.4. When MD cells were exposed to a luminal osmolarity of 180 mosM (control 300 mosM) they swelled only to 1.19 ± 0.02 of the control value and with furosemide present to 1.13 ± 0.02 or with low NaCl to 1.13 ± 0.01. While after 5 min of exposure values were 1.15 ± 0.03, 0.99 ± 0.02 and 1.02 ± 0.02, respectively. Addition of furosemide (10‐1M) to the luminal perfusate (300 mosM) resulted in a rapid decrease in cell height to 0.8 ± 0.02 in relation to control. When furosemide was removed cell volume was restituted (0.98 ± 0.03). When luminal perfusate was replaced by mannitol and (12 mM Na+, 7 mM CI‐) cell volume decreased to 0.83 ± 0.02 of the control value.The results of this study are in accordance with the view that the macula densa cells have a furosemide‐sensitive NaCl absorption system (cation and chloride co‐transport) across the apical membrane. The basolateral cell membrane have very rapid regulatory mechanisms which maintain the cell volume during reductions in basolateral osmolarity. The transport properties of the macula densa cells are not affected by maximal and supramaximal doses of vasopressin. These findings offer more direct support to the hypothesis that the initiation of the tubuloglomerular feedback response involve furosemide‐inhibitable uptake of sodium and chloride ions into the macula densa cells ‐ where the ions would, subsequently, be absorbed and accumulated inside the

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1988.tb08394.x

出版商:Blackwell Publishing Ltd    

年代:1988

数据来源: WILEY

摘要:

Cortical thick ascending limbs containing macula densa plaques were dissected and perfusedin vitro.Macula densa cell osmotic water permeability of the apical and basolateral membranes were measured by setting up osmotic steps across them in less than 0.1 s and following the ensuing time‐dependent cell volume changes. The results of this study are in accordance with the view that the macula densa cells have a relatively low permeability to water. Apical and basolateral osmotic water permeabilities are 2.4 and 30.4 times 10‐4cm3s‐1osMolar‐1cm‐2basement membrane area, respectively. No infoldings were taken into consideration. These water permeabilities were not affected by maximal and supramaximal doses of vasopressin. This paper provides new insight into the physiological behaviour of this small, and almost inaccessible, sensing epithelial disc of cells which improves the understanding of its participation in the juxtaglomerular feedback

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1988.tb08395.x

出版商:Blackwell Publishing Ltd    

年代:1988

数据来源: WILEY

摘要:

Interstitual fluid for measurement of colloid osmotic pressure (COP1) was collected from rat subcutis and skeletal muscle with three wick methods; saline‐soaked wicks implantedin vivo, titration with wicks preloaded with serial dilutions of rat plasma implanted postmortem (crossover method) and dry wicks implantedin vivoand post‐mortem. When compared in 12 rats, the mean subcutaneous COP1of 14.2 and 13.3 mmHg as estimated with the crossover method and dry wick method, respectively, both exceeded the 10.7 mmHg obtained in saline‐soaked wicks implanted for 60 min. Colloid osmotic pressure (COP) in fluid from dry wicks implanted subcutaneously was slightly lower than in plasma 5 min after implantationin vivo, then fell gradually, but remained stable the last 30 min of the 60 minin vivoimplantation period and the first 30 min postmortem, when again starting to rise. COP in fluid isolated from dry wicks implanted in muscle post‐mortem approached or even exceeded that of plasma, suggesting leakage of intracellular proteins to wick fluid. Electrophoresis of dry wick fluid from subcutis showed a pattern similar to that of plasma, while protein fractions not present in plasma were observed in muscle wick fluid. For measurement of COP1we recommend the use of dry wicks implanted post mortem for subcutis and saline‐soaked or dry wicks implantedin vivofor 90–120 min for skel

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1988.tb08396.x

出版商:Blackwell Publishing Ltd    

年代:1988

数据来源: WILEY

摘要:

The effects of neuropeptide Y (NPY) on preparations of isolated longitudinal and circular smooth muscle from rabbit urethra were studied. In both types of muscle, electrically induced contractions and relaxations could be abolished by tetrodotoxin, (TTX). In the longitudinal muscle preparations the contraction was slightly reduced by prazosin, but markedly reduced by scopolamine and NPY. The NPY effect was not influenced by pretreatment with rauwolscine. Pretreatment with NPY had no effect on contractions induced by noradrenaline (NA) or carbachol and the peptide did not relax preparations contracted by these agents. In circular muscle an initial, fast response, not sensitive to prazosin or scopolamine was occasionally observed following electrical stimulation. A slow contraction component was regularly seen; this response was abolished by prazosin. Neuropeptide Y did not influence any of these responses. The preparations were concentration‐dependently contracted by NA, whereas carbachol had no effect. Pretreatment with NPY did not affect contractions induced by NA, nor did the peptide relax NA‐contracted preparations. In neither longitudinal nor circular muscle strips did NPY affect the electrically induced TTX sensitive relaxation of NA‐contracted preparations. The results suggest that in the rabbit urethra NPY reduces contractions in the longitudinal muscle layer by selectively inhibiting the release of acetylcholine from cholinergic nerves. Neuropeptide Y did not appear to have any significant postjunctional effects nor to interfere with the release, or effects of NA or other transmitter agents. The physiological importance of the urethral effects of NPY remains to be establ

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1988.tb08397.x

出版商:Blackwell Publishing Ltd    

年代:1988

数据来源: WILEY

摘要:

The possible occurrence of non‐adrenergic mechanisms in the sympathetic vascular control of the nasal mucosa was studiedin vivousing reserpine‐treated pigs (1 mg kg‐1, i.v., 24 h earlier) in combination with pharmacological blockade of alpha‐adrenoceptors by local phenoxybenzamine (1 mg kg‐1, i.a.) infusion. The nasal mucosal depletion (99%) of the content of noradrenaline (NA) in reserpinized animals was not influenced by preganglionic denervation while the depletion (44%) of neuropeptide Y (NPY) was prevented. Upon stimulation with single shocks, 25% of the arterial blood flow reduction and 47 % of the nasal mucosal volume reduction (reflecting contraction of venous sinusoids) were still present after reserpine as compared with controls. In reserpinized animals, the vascular responses were slow developing and long‐lasting, and about 60% remained at 0.59 Hz and more than 80% at 6.9 Hz. The vascular effects after reserpine were, however, subjected to fatigue, which may explain why phenoxybenzamine treatment still reduced the functional effects in the absence of NA. Local intra‐arterial injections of NA, NPY and the metabolically stable adenosine‐5′‐triphospate analogue alpha, beta‐methylene ATP (mATP) caused reduction in both arterial blood flow and nasal mucosal volume. The C‐terminal fragment of NPY (NPY 13–36) also induced nasal vasoconstriction although with a fivefold lower potency than NPY 1–36. Adenosine‐5′‐triphosphate caused a biphasic vascular effect with vasodilatatory actions at low doses and a short‐lasting vasoconstriction followed by vasodilatation at very high doses (100‐fold higher than the threshold response to mATP). In contrast to the response to NA, the long‐lasting vascular effects of NPY and mATP were resistant to phenoxybenzamine treatment.In conclusion, although NA is likely to mediate most of the sympathetic vascular responses to low‐frequency stimulation in the pig nasal mucosa, a large resistance and capacitance vessel component upon high‐frequency stimulation seems to be non‐a

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1988.tb08398.x

出版商:Blackwell Publishing Ltd    

年代:1988

数据来源: WILEY

摘要:

An arterial and venous microcannulation technique was developed for circulatory studies in the cat gastrocnemius muscle which, based on detailed morphological and functional observations of the microvascular arrangement, seems to permit continuous recordings of pressure in arterioles (diameter ± 25 μm) and capillary pressure. These variables in combination with measurements of arterial and venous pressure and blood flow provided a means of continuous simultaneous recordings of total as well as segmental resistances in defined sections of the vascular bed, viz. in large arterial vessels (diameter ± 25 μm), arterioles (± 25 μm), and on the venous side. This new technique was applied to a study of the site(s) of autoregulatory reactions along the vascular bed evoked by changes of arterial pressure over the range 50–150 mmHg. The results indicated that active autoregulation mainly occurred within arterioles smaller than about 25 μm. In larger arterial vessels concomitant moderate active smooth muscle adjustments barely balanced out the pressure‐induced passive calibre changes, and the venous vessels did not seem to contribute actively to autoregulation, but exhibited a passive change in postcapillary resistance (Rven). The described pattern of response results in quite effective autoregulation of blood flow and capillary pressure (PC). The observed passiveRvenchange, via its effect on the pre‐ to postcapillary resistance ratio, seems to explain the fact that autoregulation ofPccan be more efficient than flow autoregulation. The study also provided quantitative data for the level of active intrinsic vascular tone in defined consecutive sections of the muscle vascular bed at normal arterial pressure and for segmental redistributions of tone evoked by pressure

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1988.tb08399.x

出版商:Blackwell Publishing Ltd    

年代:1988

数据来源: WILEY

摘要:

The influence of prolonged low‐frequency, low‐intensity electric stimulation of the gastrocnemius muscle or of the biceps femoris muscle on blood pressure and heart rate was investigated in unanaesthetized, spontaneously hypertensive rats (SHR). In both groups, elevations of blood pressure and heart rate were elicited during the 60 min of muscle stimulation. After cessation of the stimulation, a depressor response developed within 60 min. Thirty to sixty minutes post‐stimulation the fall in blood pressure was 19 ± 3 and 17 ± 4 mmHg, respectively (mean ± SE) compared with controls. In both groups, the depressor response lasted for over 5 h. In addition, the gastrocnemius‐stimulated animals also developed a post‐stimulatory bradycardia. In one group of SHR the sciatic nerve was anaesthetized with bupivacaine. The arousal response during stimulation was similar to that in the other groups, but after termination of stimulation blood pressure returned to the control level without any further drop.To investigate further the neurotransmitters involved, one group of gastrocnemius‐stimulated SHR was given naloxone by infusion during the stimulation. A modest post‐stimulatory blood pressure fall also occurred in this group, but it lasted only 90 min. Another SHR group was pre‐treated with parachlorophenylalanine, a serotonin synthesis blocker, which completely abolished the post‐stimulatory depressor response. These results indicate that prolonged muscle stimulation gives rise to a post‐stimulatory long‐lasting drop in blood pressure and that this response is mediated by somatic nerve afferents. Involvement of the endorphin and serotonin s

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1988.tb08400.x

出版商:Blackwell Publishing Ltd    

年代:1988

数据来源: WILEY