摘要:

AbstractThe effect of aminoguanidine, an inhibitor of diamine oxidase (E.C. 1.4.3.6.) on the catabolism of14C‐histamine has been studied in goats, a species in which oxidative deamination dominates, and pigs, a species in which methylation is the most important route of inactivation. In aminoguanidine treated goats the total14C‐imidazoleacetic acid (14C‐ImAA) in urine was reduced from about 70% to about 4% and in pigs from 18% to 2%. In goats the decrease in the formation of14C‐ImAA was partly compensated by an increased methylation though the fraction of14C‐histamine excreted unchanged was increased tenfold in the last‐mentioned species. In pigs the decrease in14C‐ImAA seemed to be fully compensated by increased methylation of histamine. The decrease in the excretion of non‐radioactive 1.4‐MeImAA in pigs and the change in the ratio:14C‐1.4‐MeImAA/14C‐1.4‐MeHi in both pigs and goats during aminoguanidine treatment indicated that oxidation of 1.4‐MeHi to 1.4‐MeImAA is partly catalyzed by enzymes sensitive to aminoguanidine. The incomplete inhibition of the14C‐ImAA formation during aminoguanidine treatment indicates that enzymes other than diamine oxidase might participate in the

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1973.tb05428.x

出版商:Blackwell Publishing Ltd    

年代:1973

数据来源: WILEY

摘要:

AbstractLeft ventricular receptors, firing in non‐medullated vagal afferents, were stimulated in chloralose‐anesthetized cats by brief aortic occlusions or by intrapericardial injections of nicotine. The induced reflex effects on heart rate, renal and skeletal muscle resistance vessels and muscle capacitance vessels were followed and compared with the reflex effects of arterial baroreceptor stimulation. Stimulation of the ventricular receptors induced a considerable reduction in heart rate, almost entirely due to vagal activation, and to a reflex dilatation of renal and muscle resistance vessels and of the muscle capacitance vessels. For a given reflex reduction of skeletal muscle flow resistance with the two reflex mechanisms, the concomitant reflex bradycardia and renal vasodilatation was more pronounced when the ventricular receptors were stimulated than upon activation of the arterial baroreceptors. The capacitance vessels seemed, however, to be engaged to the same extent from the two receptor groups. The reflex muscle dilatation, following ventricular receptor activation, was solely due to inhibition of adrenergic vasoconstrictor fibre activity with no evidence of any cholinergic vasodilator fibre activat

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1973.tb05429.x

出版商:Blackwell Publishing Ltd    

年代:1973

数据来源: WILEY

摘要:

AbstractCirculatory responses to shortlasting occlusions of one coronary artery (left anterior descendent or right coronary artery) were studied in chloralose‐anesthetized cats. — When the carotid sinus baroreceptors were left functionally intact, coronary occlusion induced moderate reflex reductions of heart rate and blood pressure and slight increases of resistance and capacitance vessel tone in the calf muscles. When the buffering influences from the baroreceptors were largely eliminated by bilateral carotid occlusion, the reflex fall of blood pressure and heart rate became more pronounced and a clearcut vasodilatation was now observed. After cold block of the cervical vagi, the blood pressure fall upon coronary obstruction was markedly diminished, the heart rate response was reversed to a slight tachycardia and a marked peripheral vasocon‐striction ensued. After i.v. administration of local anesthetics (lidocaine 3–4 mg/kg b.wt.) the reflex response to coronary obstruction and to shortlasting occlusions of the ascending aorta were almost completely eliminated. — It is concluded that acute occlusions of one coronary artery induce a reflex bradycardia and vasodilatation, in all probability due to activation of left ventricular mechanoreceptors. The vascular responses in this inhibitory reflex seem to be significantly moderated by influences from the arterial baro

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1973.tb05430.x

出版商:Blackwell Publishing Ltd    

年代:1973

数据来源: WILEY

摘要:

AbstractNo evidence of efferent inhibitory activity on eel lateral line sensory cells has been found in a number of different types of experiments. Proximal transection of the lateral line nerve induces no changes in the ongoing activity from the sensory cells, even in the uncurarized, un‐anesthetized animal. Stimulation of peripheral nerve filaments induces no inhibition of afferent spontaneous and/or evoked activity, either ipsilaterally or contralaterally. No spontaneous or evoked efferent activtiy could be recorded from proximal nerve filaments. Antidromic invasion of sensory terminals resets the ongoing spontaneous activity. In the intervening interval the mechanical and electrical thresholds of these sensory units are similarly elevated. Antidromic invasion is suggested to be the phenomenon reported as peripheral inhibition by Hashimotoet al.(1970

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1973.tb05431.x

出版商:Blackwell Publishing Ltd    

年代:1973

数据来源: WILEY

摘要:

AbstractThe central nervous effects of electrical stimulation of the Nn. lat. posteriores have been investigated. Maximal field potential amplitudes were found in the medial part of the ipsilateral crista cerebellaris. The field potential evoked from stimulation of fast conducting nerve fibres consisted of an afferent pre‐synaptic volley and a post‐synaptic complex wave. The latter is shown to consist of a population EPSP and a population spike in subcristal neurones. Excitatory activity from the contralateral nerve impinges on the same neurones, and bilateral summation occurs. The contralateral field potential reverses more superficially than does the ipsilateral field. Post‐excitatory reduction of population spike can be explained by refractoriness. The crista region was investigated with conventional light and electron microscopical methods. Myelinated primary afferent axons from the R. lat post. N. X. terminate in the subcristal region on the ipsilateral side. Subcristal cells have dendritic ramifications in the molecular layer. Unmyelinated axons in this layer partly consist of lateral line primary afferents. These axons differ from the cerebellar parallel fibres by their extensive branching and irregular directional architecture. Fusiform swellings of these axons establish abundant isomorphous synapses with dendritic spines. The distribution of field potential negativity in depth corresponds to the distribution of subcristal neu

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1973.tb05432.x

出版商:Blackwell Publishing Ltd    

年代:1973

数据来源: WILEY

摘要:

AbstractThe histamine contents of liver and blood of turtles(Pseudcmys scripta elegans)kept at 20–22° C were compared with those of turtles exposed to cold (4–6° C) for 2–21 days or sub‐merged for 12 hours. Submersion and cold exposure consistently caused a decrease in the histamine content of blood and an increase in the histamine content of liver. The average histamine content of blood was reduced to about half its pre‐exposure value and that of liver was doubled. The results indicate that the basophil leucocytes, which are exceptionally numerous in this species and are the only blood cells known to contain appreciable amounts of histamine, accumulate in the liver when the turtles are submerged or exposed to cold. Influence of cold exposure on the histamine content of liver and blood was also studied in several other species of turtle(Chrysemys picta, Emys orbicularis, Clcmmys caspica leprosa, Terrapcne Carolina, Kinosternon flaucscens), and they all showed a response similar to that observed inPseudemys scri

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1973.tb05433.x

出版商:Blackwell Publishing Ltd    

年代:1973

数据来源: WILEY

摘要:

AbstractDrugs known to inhibit the extra‐neuronal uptake of noradrenaline were given to the sympathetically stimulated, perfused rabbit heart, and the subsequent change in the overflow of transmitter was studied. Normethanephrine (10‐5M) increased the outflow of noradrenaline on nerve stimulation by about 25%, while lower doses were ineffectual. However, in the dose mentioned, the drug did not potentiate the earlier reported increase in overflow caused by desmethylimipramine (5.5 × 10‐7M). On nerve stimulation, intact noradrenaline made up 83% of the increase in radioactivity in the perfusate before, and 94% after, inhibition of the extra‐neuronal uptake of noradrenaline. It is concluded that extraneuronal uptake of noradrenaline, released by sympathetic nerve stimulation, plays a small but significant role in the inactivation of the transmitter from the neuro‐effector junctions. The findings are discussed with regard to earlier observations where phenoxybenzamine, another potent inhibitor of extra‐neuronal uptake, was found to increase the overflow of transmitter on nerve stimulation more than could he expected from its uptake‐inhibiting pr

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1973.tb05434.x

出版商:Blackwell Publishing Ltd    

年代:1973

数据来源: WILEY

摘要:

AbstractCholinesterase activities of homogenates of rat brain and superior cervical ganglion were measured by automatic titration at pH 8. Acetylcholine, acetylthiocholine, acetyl‐β‐methylcholine, propionylcholine, propionylthiocholine, α‐naphthyl acetate, butyrylcholine, butyrylthiocholine and benzoylcholine were used as substrates. As selective inhibitors of specific and nonspecific cholinesterases, 1: 5‐bis‐(4‐allyl dirnethylammoniumphenyl) pentan‐3‐one diiodide (284 C 51) and tetra‐isopropylpyrophosphoramide (iso‐OMPA) were used, respectively. Acetyl‐β‐methylcholine and α‐naphthyl acetate were mainly split by specific cholinesterase, butyrylcholine was predominantly hydrolyzed by non‐specific cholinesterase, while acetylcholine, acetylthiocholine, propionylcholine and propionylthiocholine were readily split by both enzymes. Michaelis—Menten constants, determined by the Lineweaver‐Burk procedure, were equal for acetylcholine and propionylcholine, on the one hand, and for acetylthiocholine and propionylthiocholine, on the other. The specific (284 C 51‐sensitive) components of the cholinesterase activities of these 4 substrates showed strong inhibition by excess substrate, while the non‐specific activity towards the same substrates increased with increasing substrate concentration. When 2 of these substrates were in turn used together as substrates, no additive increase of activity was observed. It is concluded that propionylcholine and propionylthiocholine serve, like acetylcholine and acetylthiocholine, as substrates of both specific and non‐specific cholinestera

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1973.tb05435.x

出版商:Blackwell Publishing Ltd    

年代:1973

数据来源: WILEY

摘要:

AbstractThe effects of stimulation of the cervical sympathetic chain on blood flow through the retina, the different parts of the uvea, different parts of the brain and some other tissues were studied in cats. 5 Hz reduced the oxygen tension in the vitreous body close to the retina in 5 expts. of 6. 15 μm labelled microspheres were used for quantitative determinations of blood flow. Unilateral stimulation at 10 Hz was performed for 1 min in 9 normocapnic and in 4 hypercapnic cats and for 15–30 min in 5 normocapnic cats. The results suggest that blood ffow through the innermost layers of the retina is influenced by sympathetic stimulation. The vascular resistance within the uvea was much increased in all three groups with no indications for “autoregulatory escape”. The effect was most pronounced in the ciliary processes and least in the ciliary muscle. “Autoregulatory escape” was seen in the parotid gland, the tongue and the masseter muscle, where 1 min stimulation caused mean reductions in blood flow by 82–99% compared to 6–56% after 15–30 min stimulation. Cerebral blood flow showed no statistically significant reductions in either group indicating a quantitatively minor role for the sympathetics in regulation of total cerebral bl

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1973.tb05436.x

出版商:Blackwell Publishing Ltd    

年代:1973

数据来源: WILEY

摘要:

AbstractThe effects of the regional sympathetic vasoconstrictor fibres on the consecutive vascular sections of the small intestine of the cat were studied during a 2–2.5 h hemorrhagic hypotension using a plethysmographic technique. The constrictor fibres were intermittently stimulated at 4 Hz before, during and after a hypotensive period at approximately 60 or 40 mm Hg. The nervous responsiveness of the resistance vessels and of the capacitance vessels declined continuously throughout the hypotensive period, the rate of decline being higher the lower perfusion pressure and the lower the arterial blood pH. The capillary filtration coefficient (CFC), reflecting the tonus of the “precapillary sphincters”, was increased during the hypotensive period. Nervous activation reduced CFC throughout the experiments. Tissue volume increased continuously during the latter half of most experiments at 40 mm Hg, probably reflecting a deranged Starling equilibrium across the capillary wall. During the post‐hypotensive control period after a 40 mm Hg hypotension arterial blood pressure fell rapidly. Mucosal ulcerations were regularly found in these animals and the pathogenesis of these lesions is tentatively di

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1973.tb05437.x

出版商:Blackwell Publishing Ltd    

年代:1973

数据来源: WILEY