摘要:

The influence of elevated substrates (glucose, β‐hydroxybutyrate and palmitate) on the gated. The oxidation of14C‐glucose to14CO2was depressed in diabetic aorta at a glucose concentration of 5.6 mM in the incubation medium. The glucose oxidation in normal and diabetic aorta was not affected by raising the glucose concentration of the medium to 22.2 mM. The oxidation of14C‐β‐hydroxybutyrate (0.5 and 1.5 mM) to14CO2was impaired in diabetic aorta, while the oxidation of14C‐palmitate (0.5 and 1.0 mM) to14CO2was unaltered. The oxidation of both substrates was concentration dependent. The glucose oxidation in normal rat aorta was reduced by addition of 3.0 and 6.0 mM of β‐hydroxybutyrate to the incubation medium, while 1.5 mM palmitate had no effect on the glucose oxidation. After incubation of normal rat aorta in MEM with glucose (20.0 mM) for 46 h the subsequently determined glucose oxidation was not influenced in comparison to the aorta incubated in 5.6 mM glucose. Incubation with 6.0 mM β‐hydroxybutyrate or 1.5 mM palmitate did not affect the aortic glucose oxidation. In rats which were infused for 24 h with glucose or β‐hydroxybutyrate to obtain diabetic levels of these substrates, there was no change in the aortic glucose oxidation compared to saline‐infused controls. The present results suggests that the lowered glucose oxidation in diabetic vascular tissue is not caused by hyperglycemia or high concentrations of ketone bodies or free fatty acids

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1983.tb07347.x

出版商:Blackwell Publishing Ltd    

年代:1983

数据来源: WILEY

摘要:

Renal blood flow (RBF) is markedly reduced in kidneys with unilateral ureteral obstruction (UUO), possibly due to vascular constriction. Whether obstructive nephropathy is associated with impaired RBF autoregulation is unknown. We therefore investigated RBF autoregulation in obstructed and contralateral unobstructed rat kidneys during and following release of 24 h and 6 days of UUO, using stepwise reduction of renal arterial pressure and electromagnetic recording of RBF. The lower pressure limit of autoregulation was increased and the maximal vasodilatory ability in response to infusion of acetylcholine into the renal artery was reduced only in the unobstructed kidney at 24 h of UUO. Thus, we conclude that the vasodilatory reactions to both these maneuvres, previously observed to be markedly reduced during acutely elevated ureteral pressure (Hope&Clausen 1982), were reestablished: In the obstructed kidneys in less than 24 h (RBF ˜70% of control) and in the contralateral unobstructed kidneys in less than 6 days (RBF ˜140% of control). Infusion of the thromboxane A2(TXA) synthetase inhibitors imidazole and 3‐ethyl pyridine in controls and at 24 h and 6 days of UUO did not produce renal vasodilation. These results do not support the suggestion that TXA contributes directly to the increase in renal vascular resistance observed during or following release of UUO in the

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1983.tb07348.x

出版商:Blackwell Publishing Ltd    

年代:1983

数据来源: WILEY

摘要:

The electrical and mechanical activity of fine bundles of the bovine retractor penis muscle (rp) were investigated with the sucrose‐gap technique. The main results were: the muscle displayed prominent automaticity. It showed a vigorous and long lasting active response to stretch. Phasic contractions of the rp were associated with electrical firing while tonic contractions were not necessarily correlated to spike activity. Stimulation of excitatory nerves induced excitatory junction potentials (EJP). Single EJPs could elicit spikes and repetitive firing with long lasting contraction. The EJPs were abolished by phentolamine and adrenergic neuron blocking agents. Physostigmine suppressed EJPs while scopolamine and atropine enhanced them and counteracted the effect of physostigmine. This points to an endogenous neurogenic prejunctional muscarinic suppression of the excitatory adrenergic neurotransmission. Inhibitory nerve stimulation could produce an inhibitory junction potential (IJP). However, the inhibitory nerves may also act on the contractile process without an IJP as a necessary ste

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1983.tb07349.x

出版商:Blackwell Publishing Ltd    

年代:1983

数据来源: WILEY

摘要:

The effects of chronic ganglioside treatment GM‐1 (10 mg/kg, i. p., once daily for 56 days) have been evaluated on the degenerative and regenerative features of nigrostriatal dopamine (DA) neurons following a partial lesion by tyrosine hydroxylase immunocytochemistry in combination with morphometrical analysis and by quantitative DA receptor autoradiography. Chronic GM‐1 treatment resulted in the maintenance in the number of DA cell bodies, terminals and striatal area on the lesioned side and also increased dendrite length of the DA nerve cells in the zona reticulata on that side. The lesion induced DA receptor supersensitivity was counteracted by chronic treatment with GM‐1 and the apomorphine induced rotational behaviour was significantly reduced. The hypothesis is introduced that following ganglioside treatment some lesioned DA nerve cells do not degenerate, but elongate their dendrites to give increased trophic support to DA cell bodies with intact DA axons. These increased dendro‐dendritic interactions may enable the unlesioned DA cells to increase the density of their striatal nerve terminal networks via collateral sprouting leading to recovery of dopaminergic synaptic function as evidenced in the receptor autoradiographical and behavioural analysis. Gangliosides may therefore possibly represent a new type of drug in the treatment of Parkinson's disease and aging processes in DA

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1983.tb07350.x

出版商:Blackwell Publishing Ltd    

年代:1983

数据来源: WILEY

摘要:

Contrast sensitivity to luminance‐modulated blue, green, red, and neutral gratings was measured at different spatial frequencies and eccentricities within 0–86 deg in the temporal visual field. Contrast sensitivity to gratings of constant area and spatial frequency was independent of wavelength composition but decreased with increasing eccentricity. When the gratings were scaled by the magnification factor of the human striate cortex to produce cortically similar stimulus conditions at different eccentricities (M‐scaling), contrast sensitivities became independent of visual field location irrespective of grating colour. Using colour naming we found, in accordance with previous studies, that hue changed and saturation decreased when the eccentricity of a constant‐size grating field increased. In contrast, the hue and saturation of M‐scaled grating fields were independent of eccentricity. The results suggest that the effects of eccentricity on photopic colour vision can largely be counteracted by M‐scaling which adjusts the spatial aspects of stimuli with respect to the decrease in ganglion cell density and increase in receptive field size towards the periphery of the v

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1983.tb07351.x

出版商:Blackwell Publishing Ltd    

年代:1983

数据来源: WILEY

摘要:

The objective of this study was to explore the vascular reactions in the small intestine and the possible role of sympathetico‐adrenergic influences. The experiments were performed on 23 cats. The small intestinal blood flow was estimated using a drop counting technique. In one series of cats (n=7) the small intestine and the adrenal glands had intact vascular and nervous supply (I), in another series (n=7) the small intestine was sympathetically denervated and the adrenal vessels ligated (II), and in a third series (n=9) the small intestine was innervated but the adrenal vessels ligated (III).The septic state was induced by i. v.infusion of live E.coli bacteria for two hours. The small intestinal blood flow decreased and intestinal blood flow resistance increased in all series within 3 min upon bacterial infusion. The intestinal vasoconstriction was maintained in cats with intestinal denervation as well as in cats with the adrenal vessels ligated, favouring that other humoral factors than catecholamines are involved. During the later phase of bacteremic shock the intestinal blood flow remained in the preseptic range in the series with a denervated small intestine and ligated adrenals as well as in intact cats, but declined gradually and significantly in cats with adrenal ligation only (III).This pattern of reactions favours a local rather than a remote sympathetico‐adrenal influe

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1983.tb07352.x

出版商:Blackwell Publishing Ltd    

年代:1983

数据来源: WILEY

摘要:

In order to study the excitation of intradental nerves by fluid flow in dentinal tubules the following experiments were performed. The fluid flow was caused by reduced hydrostatic pressure applied to the exposed dentine surface of the canine teeth in the anesthetized cat. In one series of 7 cats the intradental nerve activity was recorded by means of electrodes inserted in dentinal cavities. Provided that the pressure was sufficiently reduced and applied to acid‐etched dentine in preparations of sufficient depth, intradental nerve activity of different impulse amplitudes was recorded. The responding pressure sensitive units were found to be sensitized by a brief local application of veratrine and desensitized by potassium chloride. In the second series 26 single functional pulp nerve fibre units were dissected from the inferior alveolar nerve in 7 cats. Nerve impulses were recorded by means of platinum‐iridium wire electrodes. The conduction velocities of the 9 fibres responding to reduced pressure varied from 8.3 to 43.0 m/s. Five of these fibres also responded to elevated pressure. None of the 9 fibres conducting impulses with a velocity below 2 m/s responded to a reduction in pressure. Thus, the present data strongly suggest that intradental nerve endings with myelinated axons are activated by fluid flow in dentinal tubules. Our results support the hydrodynamic mechanism of dentine sensitiv

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1983.tb07353.x

出版商:Blackwell Publishing Ltd    

年代:1983

数据来源: WILEY

摘要:

Calcium infusion imply a risk for cardiovascular complications. To avoid the risks, we have developed a new method for calcium infusion in man which can keep ionized calcium concentration in whole blood (WB‐Ca++) in a steady state at a predetermined level. A solution of calcium chloride (Calcii chlor. Nord.), containing 0.117 mmol Ca++/ml water, is infused intravenously by means of an IMED 922H infusion pump. WB‐Ca++is determined every 5–10 min with a calcium ion‐selective electrode, NOVA 2®.The infusion rate is continuously adjusted. With the same initial infusion rate, 0.31 mmol Ca++/kg b. w./hour, hypercalcemia that is WB‐Ca++above 1.27 mmol/1 was reached within 10 min in healthy volunteers, 8 females with a mean age of 26 years (range 19–36) and 7 males with a mean age of 29 years (range 25–34).The presettled WB‐Ca++level, 1.45 mmol/1, was obtained within 25 min and maintained in a steady state for 155 min at 1.45 ± 0.01 mmol/1 (mean ± SE) in the females and at 1.46 ± 0.01 mmol/1 in the males. The range of the individual steady state mean WB‐Ca++was 1.42 ± 0.02 to 1.49 ± 0.02 mmol/1.No side‐effects of the infusion were noted except for a slight increase in systolic and diastolic blood pressure 60 min after start of the infusion. In conclusion, the calcium clamp technique is safe and suitable for such situations where a presettled easily controlled

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1983.tb07354.x

出版商:Blackwell Publishing Ltd    

年代:1983

数据来源: WILEY

摘要:

Electrical current pulses of quite variable duration have been used in activation of intradental nerves both in human subjects and experimental animals. It seems, however, that little information is available about the effect of pulse duration on the responses of single pulp nerve units. The aim of the present study was to investigate the effect of pulse duration on excitation thresholds of intradental A‐and C‐fibres in the cat. In 12 anesthetized cats 61 C‐and 53 A‐nerve units were identified and recorded. Electrical thresholds were determined with current pulses of different duration from 0.2 to 50.0 ms. The maximal stimulus intensity was 200 μA.Conduction velocities of all recorded units and absolute refractory periods of 20 A‐and 20 C‐units were determined. Intradental A‐and C‐fibres had different strength‐duration properties. With all pulse durations A‐fibres had the lowest thresholds. Part of the C‐fibres did not respond to the shortest current pulses even with the maximum stimulus intensity (200 μA).With 0.2 ms pulses only 31.1% of the recorded C‐fibres could be activated. In some A‐fibres a single current pulse of long duration was capable of inducing several action potentials, when the stimulus intensity was increased suprathreshold. Refractory periods of A‐units were<2.0 ms and those of C‐units 5.0–9.0 ms. It is concluded that in electrical stimulation of teeth duration of current pulses strongly affects responses of single intradental fibre units. With long pulses function of A‐fibres is pronounced because of repetitive firing in some units. These properties of pulp nerves should also be considered, when electrical st

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1983.tb07355.x

出版商:Blackwell Publishing Ltd    

年代:1983

数据来源: WILEY

摘要:

In experimental animals the jaw‐opening reflex in response to stimulation of pulp nerves has been used as a nociceptive reflex. However, there seems to be only scanty information about the amount and types of pulp nerve fibres that mediate the reflex. In the present work on 8 anesthetized cats electrical thresholds of single functional pulp nerve units were compared to the thresholds of jaw‐opening reflex. Monopolar cathodal current pulses were applied to each canine tooth. Reflex responses of the digastric muscle were recorded. The inferior alveolar nerve of the left side in 3 cats was exposed for nerve dissection and responses of pulp nerve units coming from the lower left canine tooth were recorded. The mean threshold of the jaw‐opening reflex with 10 ms pulses was 5.9 ± 3.0 (SD) μA.Below or at that level only part of the fast conducting pulp nerve units could be activated. Thresholds of A‐(n=32) and C‐(n=24) fibres were 9.9 ± 5.7 and 37.4 ± 14.5 (SD) μA respectively. Nerves of the periodontal tissues (20 units recorded) were not activated with current pulses of up to 200 μA applied to the tooth. Consequently, at threshold level the jaw‐opening reflex in response to the present type of stimulation is mediated by the fast conducting intrad

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1983.tb07356.x

出版商:Blackwell Publishing Ltd    

年代:1983

数据来源: WILEY