摘要:

AbstractCurrent theories concerning the olfactory transduction process are discussed. A hypothesis is formulated, according to which the olfactory receptor membrane contains regions where it has the structure of a lipid‐protein coacervate. Such structures may well occur in living cells. Such a membrane would have the ability to change its permeability in response to odorants and a sensitivity comparable to that of the sense of smell. The model also explains the fact that different receptor cells have different sensitivity patterns towards odorants. The model is consistent with the results of experiments that seek to establish the locus of odorant actio

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1977.tb10363.x

出版商:Blackwell Publishing Ltd    

年代:1977

数据来源: WILEY

摘要:

AbstractThe twenty‐four hour variation in concentration and output of total protein, lactate dehydrogenase and alkaline phosphatase has been studied in the peripheral lymph from the legs of 5 healthy volunteers over a period of five days. The highest concentration of these proteins was found in lymph collected during the first two hours after a night's rest. During the day a continuous decrease in concentration occurred without any direct correlation to lymph flow. The variation in lymph protein concentration between early morning and late day was about 40 %, lactate dehydrogenase and alkaline phosphatase about 90% and 45o, respectivel

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1977.tb10364.x

出版商:Blackwell Publishing Ltd    

年代:1977

数据来源: WILEY

摘要:

AbstractChanges in normal human leg lymph protein concentration, output, and lymph flow/lymph protein concentration relationship, as well as lactate dehydrogenase and alkaline phosphatase activity were followed during procedures known to increase capillary filtration as venous stasis, muscular exercise and warming of tissues. Lymph flow increased by 83% during two hour ergometer cycling, and by 117% during two hour warm water foot bath. During a two hour period of venous stasis lymph flow dropped by 50%. There was an increase in lymph flow during the rest period following all three types of experiment, most pronounced after foot warming. An inverse relationship between the lymph flow rate and lymph protein concentration was found. Lymph enzymes followed the same pattern of changes as total protein.

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1977.tb10365.x

出版商:Blackwell Publishing Ltd    

年代:1977

数据来源: WILEY

摘要:

AbstractThe metabolism of l‐14C‐palmitate and its metabolic interaction with U‐14C‐acetate were studied in the perfused hind‐quarter of the rat. 9% of l‐14C‐palmitate taken up was oxidized to14CO2accounting for 7% of total oxygen consumption by the perfused tissue. Most label from l‐14C‐palmitate was found in the lipid fraction of the muscle tissue. In spite of a 40% inhibition of palmitate oxidation, acetate only caused minor changes in the overall metabolism of palmitate. U‐14C‐acetate was mainly oxidized to14CO2and the oxygen consumption due to oxidation of acetate accounted for 20–30% of the total oxygen uptake. Minor amounts of14C‐acetate were found in muscle lipids. The addition of palmitate did not alter the metabolism of acetate. It is concluded that the presence of palmitate did not affect14C‐acetate metabolism, while the presence of acetate inhibited14C‐palmitate oxidation. The possible sites of interaction are discussed. The found interaction will probably not contribute to any major extent to the disturbed lipid metabolism found in animals and man during ethanol intake. No major changes in the tissue content of high‐energy phosphate compounds were found in the presence

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1977.tb10366.x

出版商:Blackwell Publishing Ltd    

年代:1977

数据来源: WILEY

摘要:

AbstractTo study the dependency of vascular smooth muscle contractions, produced by noradrenaline, on the concentration of extracellular calcium, experiments were performed on adult male Wistar rats. The hemodynamic characteristics of the isolated, perfused hindquarters were investigated from maximal dilatation up to maximal, noradrenaline‐induced constriction under constant flow conditions. Pressor responses to noradrenaline in the consecutive segments of the vascular bed (“proximal” and “distal” precapillary resistance vessels and postcapillary resistance vessels) were determined at low (0.2 mM) and at normal (1.5‐2.0 mM) Ca++concentrations in the perfusate. Dependence on external calcium is much greater peripherally. The smallest pre‐ and postcapillary resistance vessels are the most dependent while the larger, “proximal” precapillary resistance vessels are the least dependent on the availability of external calcium. The results illustrate the considerable differentiation of smooth muscle, depencling on its location along the vascular circuit. They further indicate that it is likely that the hemodynamically so important microvessels are highly dependent on extrinsic Ca++sources not only concerning their involvement of remote adrenergic control, but also in their maintenance of normally pronounce

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1977.tb10367.x

出版商:Blackwell Publishing Ltd    

年代:1977

数据来源: WILEY

摘要:

AbstractTo study the extent and time course of arterial baroreceptor threshold resetting to increases in blood pressure, renal hypertension was induced in young normotensive male Wistar rats by unilateral renal artery constriction. At different intervals after operation the extent of baroreceptor threshold resetting in the carotid sinus was examined. Experiments were performed 7, 14 and 25 days after renal artery clipping to enable baroreceptor resetting to be correlated with the rate and extent of cardiovascular changes in rats which had renovascular hypertension of identical durations (Lundgrenet al.1974). Baroreceptor thresholds in the carotid sinuses were established by progressive clamping of both carotid arteries after partial vascular isolation of the sinuses. The results show that after one week of hypertension baroreceptor resetting is only just apparent but by two weeks resetting is gross and seems to be largely completed. This parallels the adaptive changes in the hindquarters of renal hypertensive rats and it is concluded that baroreceptor resetting is a secondary phenomenon related to the structural changes induced in the vessels by the elevated blood pressure.

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1977.tb10368.x

出版商:Blackwell Publishing Ltd    

年代:1977

数据来源: WILEY

摘要:

AbstractA recent study of electrical and mechanical responses to stretch in isolated vascular smooth muscle revealed a clear‐cut and graded influence of the rate of change in length, dL/dt (Johansson and Mellander, 1975). This myogenic “dynamic” response at high rates of stretch was much more pronounced than the “static” response to constant, increased (+ 40%) length. In this previous study the mechanical responses were recorded as active force. In view of the fact that myogenic reactions in vivo must be associated with changes in vessel caliber, it was considered of interest to investigate the responses to stretch also in smooth muscle undergoing active shortening. In the present study, as in the one referred to above, electrical and mechanical activity in the isolated rat portal vein was studied by the sucrose gap method. However, in the present experiments the mechanical responses were recorded not only as active force but also as active shortening, making possible a comparison of the myogenic responses under these two types of smooth muscle contraction. Dynamic passive stretch was found to be associated with marked increases in spike discharge and mechanical activity under both these experimental conditions and the quantitative relation between spike discharge and rate of passive stretch (or shortening) was similar. Thus, active shortening of the smooth muscle did not interfere with the ability of the vessel to respond myogenically to passive stretch. A further analysis of the results suggested that, for the preparations as a whole, the dynamic excitatory response was more closely related to the rate of change of passive force, dP/dt, than

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1977.tb10369.x

出版商:Blackwell Publishing Ltd    

年代:1977

数据来源: WILEY

摘要:

AbstractThe localization of adrenergic receptors mediating a relaxing action was investigated in innervated and denervated longituclinal muscle strips from guinea pig ileum and rabbit jejunum. Denervated preparations were contracted by drugs that had a direct effect on smooth muscle cells, such as acetylcholine and histamine, but not by stimuli acting on cholinergic neurons, such as electrical field stimulation or nicotine. After blockade of β‐adrenoceptors, norepinephrine relaxed the innervated guinea pig ileum contracted by electrical field stimulation, by stimulating α‐adrenoceptors. Norepinephrine in low concentrations did not relax denervated preparations contracted by agents acting directly on smooth muscle. In high concentrations, it relaxed denervated preparations by a nonadrenergic mechanism, resistant to α‐ and/or β‐receptor blockade, but which was also activated by l‐(3,4‐dihydroxyphenyl) ethanol. Phenylephrine only had a weak agonistic effect on the electrically stimulated innervated preparation and did not relax the denervated one. The denervated rabbit intestine contracted by acetylcholine was relaxed by norepinephrine and phenylephrine by stimulation of α‐adrenoceptors. In the innervated preparations both drugs were more effective in inhibiting contractions induced by electrical field stimulation or eserine than those induced by exogenous acetylcholine. Both the denervated guinea pig and rabbit intestine were relaxed by stimulation of β‐adreno‐ceptors. It is suggested that in the guinea pig ileum α‐adrenoceptors mediating relaxation are located only in cholinergic neurons, whereas in rabbit jejunum they are located both in these neurons and in the smooth muscle cells. Beta‐adrenoceptors are located in the smooth

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1977.tb10370.x

出版商:Blackwell Publishing Ltd    

年代:1977

数据来源: WILEY

摘要:

AbstractThe cardiovascular responses to acute mental “stress” were compared in the Milan strain of spontaneously hypertensive rats (MHS) and in normotensive control rats (NR). Blood pressure and heart rate were followed in pairs of awake MHS and NR, while defence reactions were provoked by alerting stimuli (noise, vibration). No differences were noted between the two groups in response to “stress” although resting heart rate in MHS was lower than in NR. Administration of atropine or propranolol to MHS and NR showed the MHS to have a higher resting vagal tone and lower sympathetic tone than the NR. Subsequent (at least two weeks later) hemodynamic investigation, under nembutal anesthesia, showed no difference in cardiac output between MHS and NR but a higher stroke volume, presumably related to the lower heart rate in MHS. Thus, total peripheral resistance was increased in MHS as was the ratio left ventricular weight/body weight, and in good proportion to the blood pressure rise. Thus MHS differ substantially in both their responses to “stress” and also hemodynamically from the Okamoto strain of spontaneously hypertensive rat (SHR), being the so far most studied and best known model of essential hypertension in man. In MHS the hypertension is more of a systolic type and is of primarily renal origin. As such, MHS provide another model for investigating the polygenic nature of hyperten

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1977.tb10371.x

出版商:Blackwell Publishing Ltd    

年代:1977

数据来源: WILEY

摘要:

AbstractTwo glucuronidated catechol derivatives have been identified in a transplantable islet cell tumour of the golden hamster,i.e.dopamine‐4‐O‐glucuronide and 3‐methoxytyramine‐4‐O‐glucuronide. L‐dopa is rapidly metabolized in the tumour to one or both of these glucuronides. Incubation of tumour homogenates in the presence of β‐glucuronidase shows that dopamine‐4‐O‐glucuronide is present in the tumour in extre

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1977.tb10372.x

出版商:Blackwell Publishing Ltd    

年代:1977

数据来源: WILEY