摘要:

AbstractBoth excitation and inhibition has been found in cells of origin of the ventral spino‐cerebellar tract (VSCT) to be evoked by volleys in cortico‐spinal fibres. The earliest EPSPs and IPSPs had features of disynaptically evoked postsynaptic potentials; these were, however, found only in a small proportion of cells and polysynaptic EPSPs and IPSPs were dominating. Postsynaptic potentials evoked in VSCT cells from primary afferents were effectively facilitated by cortico‐spinal volleys. The cortico‐spinal effects on VSCT cells may thus well be mediated by the same interneurones which mediate their excitation or inhibition from the periphery and which could evoke similar postsynaptic potentials in motoneurones. Generally all the observations are in keeping with the hypothesis (Lundberg 1971) that VSCT cells monitor transmission through interneurones interposed in various reflex paths to moton

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1977.tb05916.x

出版商:Blackwell Publishing Ltd    

年代:1977

数据来源: WILEY

摘要:

AbstractThe effect of “vein pump” activation upon superficial venous pressure and blood flow in human subcutaneous adipose tissue was studied in 6 normals and 2 patients with venous insufficiency. Blood flow in subcutaneous tissue was measured at the lateral malleolus by the local133Xenon washout technique. with the subject placed in a supine position. During passive lowering of the leg blood flow decreased 50 per cent and total vascular resistance increased 136 per cent. Activation of the vein pump by continuously tipping the foot up and down caused a decrease in venous pressure of 5 mmHg in horizontal position. Venous pressure increased only by 8 mmHg when the leg was lowered during exercise. In this situation blood flow remained constant corresponding to an increase in vascular resistance of 42 per cent. However increasing venous pressure to 28 mmHg by venous stasis in the lowered leg during exercise caused an additional increase in vascular resistance of 82 per cent. In the patients with venous insufficiency exercise did not prevent the decrease in blood flow during lowering of the leg. Hence venous pressure elevation of 25 mmHg or more caused an additional increase in vascular resistance in subcutaneous tissue, “vasoconstrictor response”. It is concluded that this “vasoconstrictor response” depends on a vasoconstrictor impulse transmission from veins to arterioles, veno‐arte

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1977.tb05917.x

出版商:Blackwell Publishing Ltd    

年代:1977

数据来源: WILEY

摘要:

AbstractPaired hydronephrotic (HN) and hypertrophic (HT) rat kidneys were studied after 6 days with complete unilateral ureteral obstruction without exposing the kidneys. Total HN renal blood flow (RBF), estimated by total microsphere (MS) uptake and from local125I‐antipyrine (Ap) uptake, averaged about 3/sec (n=147) for the extensor digitorum communis muscle and 3.39±0.68 m/sec (n=142) for the femoral quadriceps muscle. 4 of control. HN kidney GFR was reduced to about 1/2 of control level as estimated from inulin clearance of HT kidney times the HN to HT ratio for mean single nephron filtration rate, determined by14C‐ferrocyanide. Whereas blood flow (Ap) was proportionately reduced in outer and inner cortex (OC and 1C), fractional flow to the outer medulla (OM) was doubled as compared to controls (p0.02). Thus the results oppose the current concept that HN is characterized by disproportionate circulatory damage to IC and OM with little or no filtration in deep nephrons. In HT kidneys average RBF (MS) and GFR rose by about 1/2. Whereas total blood flow (Ap) rose proportionately in OC and IC, it remained at control level in OM, indicating dissociation between the total RBF and GFR and the effective blood flow to the OM

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1977.tb05918.x

出版商:Blackwell Publishing Ltd    

年代:1977

数据来源: WILEY

摘要:

AbstractUnstimulated pairs of rat submandibular glands were compared with regard to their wet weight, total protein content and kallikrein activity quantitated by Bz‐Arg‐OEt‐esterase and kallikrein antigenic activity. Paired glands from the same animal were found to be comparable, whereas differences from one animal to another were considerable. One of two paired glands was extirpated and used as control, and the other was subsequently subjected to stimulation. Salivary secretion was induced parasympathomimetically (intraperitoneal injections of pilocarpine; perfusion with acetylcholine and electrical stimulation of the ductal nerve plexus near the gland hilus) or sympathomimetically (cervical sympathetic nerve stimulation with or without administration of α or β‐adrenergic blocker; perfusion with epinephrine, norepinephrine or isoproterenol). The effect was studied by measuring the change in total gland kallikrein content and by quantitation of kallikrein in saliva. A small secretion of kallikrein was always observed. However, oc‐adrenergic stimulation was 40 and 1500 fold more effective in releasing kallikrein than β‐adrenergic and parasympathomimetic stimulation, respectively. Also, significantly more kallikrein was released by β‐adrenergic than parasympathomimetic stimulation. Immunohistochemistry confirmed the observed depletion of kallikrein following α‐adrenergic stimulation. No alteration in kallikrein localization was observed

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1977.tb05919.x

出版商:Blackwell Publishing Ltd    

年代:1977

数据来源: WILEY

摘要:

AbstractInfusions (20μl/min) of hypertonic (0.3 M) NaCl and angiotensin 11 (1 ng/kg min‐1)in isotonic (0.15 M) NaCl were made for 1 h in the hydrated goat during fully developed water diuresis. Either H2O or deuterium (D2O) was used as solvent. A pronounced antidiuretic response, outlasting the infusion period by 30 min or more, was seen when the substances were dissolved in H2O. Only a weak inhibition of the water diuresis, which was extinguished during the infusion period, was obtained when D2O was used as the solvent. The infusion of 0.3 M NaCl/H2O invariably induced drinking in one of the goats, which, however, showed no drinking response to the infusions of 0.3 M NaCl/D2O. The possibility is discussed that D2O (perhaps by‐its inhibitory effect on (Na+‐K+)‐ATPase activity) reduced the sensitivity of juxtaventricular receptors regulating ADH‐release and wa

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1977.tb05920.x

出版商:Blackwell Publishing Ltd    

年代:1977

数据来源: WILEY

摘要:

AbstractThe synthesis and the utilization of noradrenaline in the caudal and cranial part of intact and sectioned rat spinal cords were determined at 20 h or for 30 min ‐ 2 h after an operation. The synthesis and the utilization of noradrenaline in the caudal pari of spinal cords transected 20 h previously were retarded as compared to those in the cranial part of sectioned cords or in the caudal part of intact cords. The synthesis of noradrenaline was stimulated in the caudal and cranial part of the spinal cord when measured for 30 min after a transection. The utilization of noradrenaline in the spinal cord caudal to a transection was not decelerated during 2 h after an operation. Local application of lidocaine to the cord prior lo the cut changed the synthesis and the utilization of noradrenaline in both parts of the spinal cord to values similar to those obtained 20 h after the operation. Transection of the spinal cord might stimulate the synthesis and the utilization of noradrenaline by a shortlasting mechanical irritation of neurons cut by the lesio

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1977.tb05921.x

出版商:Blackwell Publishing Ltd    

年代:1977

数据来源: WILEY

摘要:

AbstractThe effect of urea on the electrophysiological properties of the frog muscle cell membrane was studied with intracellular microelectrodes, together with an analysis of the electrolyte composition of the muscle. The different parameters were measured and evaluated after soaking the muscle for 60 min at urea concentrations up to 2.25 M. The resting membrane potential was markedly decreased above 1.50 M and fell to about ‐50mV at 2.25 M. The specific membrane resistance (Rm) was almost unaffected at concentrations of 0.75 M and 1.50 M but was reduced after 60 min in 2.25 M to very low values indicating a leaky membrane. The maximum rate of rise of the action potential (Rm) was unaffected up to 0.50 M but was reduced to about 50% of control value at 0.75 M. Between 0.75 M and 1.25 M it was constant and at higher concentrations reduced to almost zero. The reduction ofVAat the lower concentrations was not accompanied by changes in neither the resting membrane potential norRm. It is proposed that urea perturbs protein systems concerned with the generation of the muscle action potential without affecting the passive electrical properties of the muscle membrane. The electrolyte analysis revealed an increase in intracellular Na+ and K+ concentrations, mainly due to loss of intracellular wate

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1977.tb05922.x

出版商:Blackwell Publishing Ltd    

年代:1977

数据来源: WILEY

摘要:

AbstractEffects of hypoxia and glucose‐free solution on the isolated rat portal vein were studied. Decrease of extracellular Po2below 50 mm Hg caused graded inhibition of spontaneous mechanical activity; below 7 mm Hg. inhibition was complete in most preparations. Contracture force of depolarized portal vein was less sensitive to decreases in Po2. Responses to noradrenaline at all concentrations were markedly depressed at extreme hypoxia. Sucrose‐gap experiments showed that hypoxia reduced the spontaneous electrical spike discharge. Mean tissue contents of PCr, ATP and glycogen (expressed as glucose) were 3.02, 2.47 and 5.07μmol/g cell wt. in spontaneously active control muscles and 1.07, 1.65 and 1.83 after 20 min anoxia. Physiological variations in Po2may influence myogenic activity of vascular smooth muscle largely through an action at the membrane level and this mechanism may participate in local blood flow control. Calculations indicated that the graded response to hypoxia in the present in vitro experiments was not due to diffusion limitation. Spontaneous mechanical activity was relatively well maintained even after prolonged exposure to glucose‐free solution, whereas the responses to K1and noradrenaline were markedly suppressed. Electrophysiological recordings during spontaneous activity indicated desynchronization and impaired conduction. PCr and ATP were maintained at control levels and glycogen reduced by 50 per cent after 2 h in glucose‐free medium. Indications of the use of amino acids (glutamate) as substrate under these conditions were

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1977.tb05923.x

出版商:Blackwell Publishing Ltd    

年代:1977

数据来源: WILEY

摘要:

AbstractEffect of denervation on accumulation of a‐aminoisobutyric acid (AIB) by the diaphragm was studied in 11‐, 21‐, 31‐, and 51‐day‐old rats. In both innervated and denervated diaphragms the accumulation steadily decreased with age. Denervation significantly enhanced accumulation at all ages, the relative increment being greater in older animals owing to the lower basal accumulation ratio for AIB. The denervation‐induced stimulation was partially abolished by dactinomycin administration. The drug obviously inhibits the formation of new carrier sites at plasma membranes for

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1977.tb05924.x

出版商:Blackwell Publishing Ltd    

年代:1977

数据来源: WILEY

摘要:

AbstractEnergy turnover in the isolated rat portal vein was investigated by measurement of oxygen consumption (Jo2) and lactate production (JLA) under simultaneous recording of mechanical activity. In spontaneous activity under aerobic conditions and at optimal muscle length Jo2and JLAwere 0.55 and 0.62/μmol/min g. respectively, corresponding to an ATP‐production of 4.3 μmol/min g. When muscle length was changed, an approximately linear relation was found between energy turnover and mean isometric tension. The tension‐independent part of ATP‐production was 3.0 μmol/min g. In Ca2+‐free solution the metabolic rate was 20 % lower still. Jo2was nearly equal in isometric contractions and in afterloaded isotonic contractions from the same initial muscle length. During a maximal tonic contracture in K+‐depolarized portal vein Jo2increased to about twice that in spontaneous activity. Changes in contracture force by variations in muscle length or in [Ca2+]0were associated with identical linear relations between Jo2and active tension. This relation was less steep than the corresponding relation for spontaneous activity. The anaerobic lactate production of the portal vein was 2.7 times the aerobic level. The accelerated glycolysis did not compensate for eliminated oxidative metabolism. Under substrate‐free aerobic conditions no lactate was produced by the muscle and compared to the control situation Jo2declined more than could be accounted for by reduced mechanical aevtivity alone. The metabolic turnover rate in relation to isometric tension is high in the rat portal vein compared to that of tonic vascular smooth muscle from larger vessels. This correlates with differences in dynamic mechanical properties. At comparable tension levels in the portal vein, the rate of cross‐bridge turnover may be higher in spontaneous phasic activity than in susta

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1977.tb05925.x

出版商:Blackwell Publishing Ltd    

年代:1977

数据来源: WILEY