Physiological characteristics of the smooth muscles vessels of the small circle of blood circulation

Now sireos problem of pulmonology there are the diseases connected with infringement of coordinated regulation of a tone of smooth muscles of vessels and airways of ways that conducts to dissociation of parameters haemodinamyc and ventilation of lungs and as consequence, to infringement airwave-perfusion attitudes. In the review features humoral regulation contractile activity of smooth muscles of vessels of a small circle of blood circulation, a role of endocellular alarm systems in these mechanisms, and endothelium, as the local modulator endocrine functions are considered. Disgusting muscles of a small circle are distinguished from the main vessels of the big circle of blood circulation with predisposition to the raised mechanical pressure. In spite of the fact that endothelium renders modulating relaxe influence on contractile answers of smooth muscles of vessels of a venous and arterial small circle of blood circulation at action corresponding vasoconstriction, pulmonary veins are capable to endothelium-dependent dilatation to a lesser degree, in comparison with pulmonary arteries. And, on the contrary, in absence endothelium, they are characterized with high sensitivity to vasopression to substances--serotonin, histamine, phenylephrine. Features of regulation smooth muscle pressure pulmonary an artery are shown in contractile reactions of its isolated segments in reply to influence beta-adreno agonist--isoprotherenol and phosphoesterase inhibitors. Though, increase in endocellular concentration cyclic nucleotides (cAMP and\or cGMP), on the standard representations, cannot explain growth of a mechanical pressure of smooth muscles, apparently, in contractile reactions of a pulmonary artery to influence biologically and physiologically active substances interfere more complex mechanisms in which basis processes of interaction of smooth muscles cells lay, endothelium and cells of a microenvironment. Finding-out of the contribution cyclic nucleotides in these processes demands the further researches.     

The role of peripheral cholinergic and adrenergic receptor systems in the action of histamine on the isolated coronary arteries

The action of peripheral cholinergic and adrenergic receptor systems on the histamine coronary vasospastic effects are investigated in the experiments on the isolated ring-shaped strips of coronary arteries of pigs with the aid of specific agonists and antagonists. It has been demonstrated that neuromediator systems play a significant role in the regulation of contractile activity of the coronary spasm pathogenesis. When medicines are prescribed to patients with ischemic heart disease it is necessary to take into account the character of the preparations interaction which affect the peripheral neuromediator processes such as histaminergic, cholinergic, adrenergic and others.     

Influence of nanosize particles of cobalt ferrite on contractile responses of smooth muscle segment of airways

Contractile responses of airways segments of porpoises inhaling nanopowder CoFe2O4 were stidued by means of a mechanographic method. Inhalation of the nanosize particles of CoFe2O4 in vivo and in vitro testing the nanomaterial on isolated smooth muscles led to potentiation histaminergic, cholinergic contractile activity in airways of porpoises and to strengthening of adrenergic relaxing answers. Nanosize particles vary amplitude of hyperpotassium reductions in smooth muscle segments of airways similarly to the effect of depolymerizing drug colchicine.     

Contractile properties of smooth muscles of bronchial tubes at formation of hyperreactance of airways

Contractile properties of smooth muscles of bronchial tubes of porpoises in formation of hyperreactance airways, were studied. Sensitization by ovalbumin results in formation of hyperresponsiveness of the airways as shown in increase in amplitude of contractile responses to histaminergic influences and oppression of adrenergic relaxations of segments. Respiratory epithelium oppresses contractile responses of airways in intact animals to histaminergic influences. Influence of epithelium on adrenergic responses depends on precontractile factor: they increase in prereduction by histamine. In formation of hyperresponse, the epithelium loses ability to modulate responses of smooth muscles of the airways. Incubation segments of smooth muscles of the airways in interleukin 5 increases contractile responses to histaminergic influences. Receptor of interleukin 5 (the soluble fraction) neutralizes the effect of exogenous interleukin 5, and incubation of receptor of sensitized animals oppresses histaminergic contractile responses.     

Pharmacological reactions of the circular muscle of the guinea pig vas deferens.

Pharmacological responses of spiral strips prepared from the guinea pig vas deferens to various adrenergic and cholinergic agonists and autacoids were studied. On the circular muscle alpha adrenergic, muscarinic cholinergic and histaminergic receptors were identified. The responses evoked on the circular and longitudinal muscles were of the same type.     

Regional and Species Heterogeneity of Vascular Responses: Cholinergic Muscarinic Regulation of Motor Function of Blood Vessels of Rat and Frog

Cholinergic muscarinic regulation of the motor function in several large blood vessels receiving adrenergic innervation of various degree of density was studied in the rat and the brown frog. The presence of the cholinergic component in the vascular nerve plexus and of muscarinic cholinoreceptors (M-ChR) in the vascular wall was studied by recording isometric contractions of isolated vessels in response to electric stimulation of nerves and to action of an agonist of M-ChR, 5-methylfurmetide, cholinomimetic ACh, and muscarinic cholinoblocker atropine. Cholinergic vasoconstrictory nerves were found in the vascular plexus of the rat portal vein and frog pulmonary artery, whereas M-ChR, in all vessels studied, whether they receive or do not receive the cholinergic vasoconstrictory innervation. The role of cholinergic nerves and the initial functional state of the vessels in the vascular reaction to stimulation of M-ChR as well as the regional heterogeneity of vascular responses and species heterogeneity of muscarinic cholinergic control associated with animal behavior and its habitat were demonstrated. The data obtained confirm the absence of uniformity in the structural and functional organization of blood vessels and, thereby, indicate differentiation of the mechanisms of vasomotor regulation in different zones of vascular bed in different species of vertebrate animals.     

Increase in the sensitivity of the vascular smooth muscle to constrictor factors after denervation and with a decrease in blood pressure

The effect of denervation on the contractile activity of the saphenous artery in normotensive rats and rats with regional hypotension was studied. Hypotension was caused by partial occlusion of the abdominal aorta distally from the renal arteries, and then, in four weeks, to denervate the saphenous artery, a portion of the femoral nerve in one of the limbs was resected. In two more weeks, the contractile responses of ring preparations of the saphenous artery (after removal of the endothelium and block of neuronal uptake and β-adrenoreceptors) were investigated under isometric conditions. In normotensive rats, the denervation led to an increase in the vascular sensitivity to norepinephrine, phenylephrine, serotonin, and KCl. Similar changes in contraction were caused by chronic hypotension; however, rats with hypotension exhibited no additional denervation-induced increase in the vascular sensitivity. After treatment with glyoxylic acid, the fluorescence intensity of the vascular adrenergic fibers adapted to a reduced pressure was lower than that in the norm. It was assumed that the vascular hypersensitivity in hypotension is caused by impairment of sympathetic innervation.     

A histochemical study of the innervation of the cerebral blood vessels in the domestic fowl

Summary Adrenergic and cholinergic nerves innervating the cerebral arteries of the domestic fowl were examined by specific histochemical techniques.The adrenergic nerve plexuses of the cerebral carotid system are markedly denser than those of other vertebrates observed by similar techniques. They form longitudinally elongated meshworks of fine fibres in the vascular wall of the arterial branches. Those innervating the vertebro-basilar system are less dense and more elongated, and, as the size of the artery diminishes, the fibres of the plexus become coarser. In the small pial and parenchymal arteries they are reduced to a few fibres running parallel to, or spiralling around the vascular axis.The cholinergic nerve plexuses are not as dense as the adrenergic system. The acetylcholinesterase activity is very weak, except in the plexuses innervating the cerebral carotid artery and the proximal portion of the anterior and posterior rami. In the vertebro-basilar system, a few thick nerve bundles run alongside the blood vessels of the vertebral and basilar arteries. Cholinergic nerves enter the cranial cavity along the internal carotid, the vertebral and possibly the cerebro-ethmoidal arteries.Intracerebral capillaries and some arterioles are not innervated with cholinergic and adrenergic fibres of peripheral origin, but with ones arising from parenchymal nerve cells.     

Inhibition of iloprost of the contractile effect of noradrenaline in mesenteric artery rings: evidence for a possible calcium-dependent mechanism.

Iloprost caused a concentration-dependent decrease in the response to noradrenaline in the rabbit isolated endothelium denuded rings from superior mesenteric artery but not thoracic aorta. Similar inhibition was obtained by verapamil using identical concentrations. In Ca(2+)-free EGTA containing medium noradrenaline both at lower and higher concentrations elicited a reduced contractile response and further addition of Ca2+ (2.5 mM) to the medium produced a second contraction in both mesenteric artery and aortic rings which was significantly and equally inhibited by iloprost and verapamil using identical concentrations in mesenteric artery but not in aortic rings. Prior addition of iloprost to the medium did not protect the inhibitory effect of phenoxybenzamine against noradrenaline-induced contraction. These results were taken as an evidence for the possible Ca2+ entry reducing effect of iloprost in mesenteric artery but not thoracic aorta. These results were also taken as an indirect evidence supporting the hypothesis that increased synthesis of prostacyclin by noradrenaline in the vascular wall may inhibit the contractile effect of the agonist by a (-) feedback mechanism mediated by Ca2+ entry into the vascular smooth muscle.     

Angiotensin II potentiates responses of the rabbit basilar artery to adrenergic nerve stimulation

Angiotensin II has little contractile effect on the isolated rabbit basilar artery; however, it markedly potentiates contractile responses to adrenergic nerve stimulation. This is not a post-synaptic effect of angiotensin, as responses to exogenous norepinephrine are not altered. Angiotensin increases stimulation-evoked release of norepinephrine, and this effect probably accounts for the increased response to adrenergic nerve stimulation. Since sympathetic stimulation may protect the cerebral circulation from hypertensive damage, increased responsiveness to adrenergic nerve activity produced by angiotensin may have a beneficial effect.     

The wall structure of the central vein of the human adrenal glands]

The wall structure of the vena centralis in the human adrenal gland was examined by light and electron microscopy. The longitudinal smooth muscle system in the wall of the central vein was found to be incomplete, eccentric, and located far from the intima. At the junction with smaller veins the muscle system increases in size so that a thickening protrudes the intima into the lumen. A structured intercellular substance of varying width is located between the endothelium and the smooth muscle system, and unmyelinated adrenergic nerve fibres extend to the endothelium. Vasa vasorum are found only in the periphery of the vascular walls. The findings are interpreted as follows: The construction of the vein walls in the medulla of the human adrenal gland acts as a protection against the excessive contractile effect of a small to medium concentration of noradrenalin from the adrenal medulla.     

Effect of progesterone on the contractile response of isolated pulmonary artery in rabbits.

The purpose of this study was to assess the direct effect of progesterone on rabbit pulmonary arteries and to examine the mechanism of its action. Rings of pulmonary artery from male rabbits were suspended in organ baths containing Krebs solution, and isometric tension was measured. The response to progesterone was investigated in arterial rings contracted with noradrenaline (NA), KCl, and CaCl2. The effects of endothelium, nitric oxide (NO), prostaglandins, cyclic GMP (cGMP), and the adrenergic beta-receptor on progesterone-induced relaxation were also assessed. Progesterone inhibited the vasocontractivity to NA, KCl, and CaCl2, and relaxed rabbit pulmonary artery. The relaxing response of progesterone in pulmonary artery was significantly reduced by removal of endothelium, inhibitors of nitric oxide synthase and guanylate cyclase, but not by prostaglandin synthase inhibitor and blockage of the adrenergic beta-receptor. In Ca2+-free (0.1 mM EGTA) Krebs solution, progesterone inhibited NA-induced contraction that was intracellular Ca2+-dependent, but didn't affect the contraction of extracellular Ca2+-dependent component. Our results suggest that progesterone induces relaxation of isolated rabbit pulmonary arteries partially via NO and cGMP. Progesterone may also inhibit Ca2+ influx through potential-dependent calcium channels (PDCs) and Ca2+ release from intracellular stores.     

Iloprost (ZK 36374) modulates the responses to beta-adrenoceptor agonists in guinea-pig airways and pulmonary vasculature

The effect of iloprost on airway smooth muscles and its influence on the actions of beta-agonists and histamine were studied in the isolated perfused lung and isolated tracheal strips from guinea-pigs. Bolus injection of iloprost into the pulmonary artery elicited a concentration-dependent decrease in pulmonary perfusion pressure and an increase in airway resistance. These effects are not mediated through cholinergic, serotoninergic and histaminergic receptors. A rapid tachyphylaxis affected the effect of iloprost in airway resistance but not in pulmonary perfusion pressure. Iloprost did not induce a response in the isolated tracheal strips and did not alter the effect of histamine in both tracheal strips and airway resistance. This compound, however, caused an inhibition in the airway resistance-reducing effect of adrenaline and isoprenaline in the isolated perfused lung and a potentiation in the perfusion pressure-increasing effect of adrenaline. Iloprost also inhibited the relaxing effect of adrenaline and isoprenaline in the isolated tracheal strips precontracted with histamine and potentiated the inhibitory effect of propranolol against adrenaline and isoprenaline. From these results it was concluded that: Iloprost, a stable analogue of prostacyclin, modulates the beta-adrenoceptor blocking effect of propranolol in both airway smooth muscles and pulmonary vasculature.     

Vascular resistance and vasoactivity of gills and pulmonary artery of the salamander,Ambystoma tigrinum

Summary In order to understand the blood flow patterns and their regulation in the gills and pulmonary artery ofAmbystoma tigrinum, the vascular resistance and vasoactivity of the two major branchial perfusion pathways and a vascular plexus in the pulmonary artery were investigated using an isolated-tissue perfusion method. Acetylcholine and epinephrine were both pressor agents in all three vascular segments. Angiotensin II also constricted the branchial respiratory vasculature. Norephinephrine was primarily a vasodilator in the branchial respiratory vasculature, however, it had no effect on the shunt vessels of the gill or the pulmonary arterial plexus. Both gill circulations were insensitive to alterations in CO₂ and pH. Anoxia produced a slight vasodilation of the branchial respiratory vessels but had no effect on the shunt vasculature. Mild hypoxia had no effect on either branchial circulations. The results suggest that: (1) blood flow through the respiratory section of the gill may vary between 8 and 47% of total gill flow, (2) the major perfusion pathway to the lung is probably from the efferent artery of the third gill through the ductus arteriosus and then into the pulmonary artery, (3) O₂, CO₂ and pH exert no local control of branchial perfusion, (4) both cholinergic and adrenergic regulation of branchial and proximal pulmonary arterial vascular resistance is possible, (5) a rise in circulating norepinephrine should increase blood flow to the respiratory section of the gill.Abbreviations AII angiotensin II - ACh acetylcholine - EPi epinephrine - NE norepinephrine     

肺纤维化初期肺动脉高压大鼠肺动脉反应性的变化

目的：观察肺纤维化初期肺动脉高压大鼠肺动脉血管反应性的变化。方法：66只雄性SD大鼠,随机分为博莱霉素（BLM）组和手术对照（Sham）组。BLM组为气管内一次性滴注BLM（5 mg/kg）;Sham组为气管内滴注等容量的生理盐水（NS）。应用离体血管张力检测技术测定大鼠肺动脉血管反应性变化;用HE显示肺动脉壁病理形态学变化;Masson染色检测肺纤维化程度;右心漂浮导管技术测定大鼠平均肺动脉压。结果：①BLM组大鼠的肺动脉血管（保留内皮和去内皮）对苯肾上腺素（PE）的收缩反应均弱于Sham组（P均〈0.05）。②BLM组大鼠肺动脉血管（保留内皮）对氯化乙酰胆碱（Ach）的舒张反应明显弱于Sham组（P〈0.01）。③Sham组有内皮的肺动脉血管对L-NAME和PE联合作用的收缩反应明显强于PE单独作用（P〈0.01）,而BLM组有内皮肺动脉血管对L-NAME和PE联合作用的收缩反应与对PE单独作用比,其差异无统计学意义（P〉0.05）。④BLM组肺动脉内皮细胞脱落。⑤BLM组大鼠肺组织呈现纤维增生初期的病理特征,且大鼠的平均肺动脉压明显高于Sham组（P〈0.05）。结论：肺纤维化形成初期肺动脉高压大鼠肺动脉血管反应性出现异常。     

Mechanism of the serotonin effect on motility of the duodenum,ileum, and jejunum in awake rabbits

I. v. administration of serotonin to alert rabbits produced a phasic change of contractile activity of duodenum, ileum, and jejunum including excitatory and inhibitory components. It is shown that stimulation of the small bowel motility is caused by serotonin activation of non-cholinergic excitatory mechanism with participation of effector cholinergic neurones. The initial suppression of the motility is caused by participation of nonadrenergic noncholinergic inhibitory mechanism, and the secondary inhibition of contractile activity of a small bowel with serotonin has an adrenergic nature.     

Histamine releases PGI2 from human pulmonary artery

Histamine caused a triphasic response of human pulmonary artery strips in vitro, consisting of a small initial contraction followed by pronounced relaxation preceding a second contractile response. These characteristics were not seen with other contractile stimuli including 5-hydroxytryptamine, leukotriene D4, and KCl. The relaxant component of this response was ablated by removal of endothelium from the vascular strips or by pretreatment of the tissue with 1 microM indomethacin. Measurement of the PGI2 degradation product 6-keto-PGF1 alpha in supernatants from histamine-challenged tissues confirmed the synthesis of PGI2. Supernatants from unstimulated or leukotriene-challenged tissues contained no detectable amounts of 6-keto-PGF1 alpha. The histamine H1 antagonist diphenydramine inhibited both the contractile and relaxant responses to histamine whereas the H2 antagonist cimetidine affected neither component. The released PGI2 significantly altered the dose-response curve to histamine without inhibiting the maximal contractile responses. We conclude that histamine induces PGI2 formation from pulmonary arterial endothelium via an H1 receptor.     

Development of nerves plexuses in the pelvis of the prenatal rabbit

By means of neurohistological and histochemical methods using serial sections of the embryos at the age of 12-30 days of development, the premediatory and beginning of the mediatory stages in development of cholinergic and adrenergic neural plexuses have been studied in rabbit small pelvis. Appearance of catecholamine-containing cells at early mediatory stages and a gradual development and complication of the cholinergic and adrenergic neural plexuses structure are demonstrated. By birth in the rabbit small pelvis area, some elements of cholinergic and adrenergic structures begin to form.     

Fine structural and cytochemical study of the innervation of smooth muscle in an amphibian (Bufo marinus) lung before and after denervation

Summary The innervation of the toad (Bufo marinus) lung was studied with transmission electron microscopy and fluorescence techniques, both before and after 12 or 20 days close vagosympathetic denervation. Four cytologically distinct types of neuronal processes were recognised, in relation to the visceral muscles of the lung. These were described as cholinergic, adrenergic, nonadrenergic/non-cholinergic (NANC) and sensory on the basis of the characteristics of their vesicular content and cytochemical reactions. An apparent efferent innervation of visceral smooth muscle was achieved by NANC (50%), cholinergic (25%) and adrenergic (25%) fibres. A few sensory fibres were also present. After denervation only NANC fibres persisted, showing that the cell bodies of these fibres were intrapulmonary. The vascular smooth muscle was supplied by cholinergic, adrenergic and sensory fibres. In the walls of the proximal branches of the pulmonary artery were fibres containing large dense-cored vesicles. These profiles, which were associated with the vasa vasorum, were similar to neurosecretory fibres. After denervation all neural profiles associated with the vasculature had degenerated. The observations suggest that vagal vasodepressor effects in the toad lung are mediated indirectly through relaxation of visceral muscle strands which in their contracted state compress vascular channels.The authors would like to thank Dr. J.R. McLean for technical advice on fluorescence microscopy. This work was supported by a grant from the Australian Research Grants Committee     

Interaction of alpha and beta adrenergic stimulation on aortic ornithine decarboxylase activity

The interaction between beta and alpha adrenergic agonists on regulation of cockerel aortic ornithine decarboxylase (ODC) activity was examined. The beta adrenergic agonist isoproterenol both reduced basal aortic ODC activity and prevented induction of the decarboxylase by the alpha adrenergic agonist methoxamine. 3-Isobutyl-1- methylxanthine (IBMX) similarly reduced basal ODC activity and blocked induction of the enzyme by methoxamine. When given ten minutes before or after methoxamine, isoproterenol prevented aortic ODC induction, but not large sustained increases in blood pressure evoked by the alpha adrenergic agonist. In contrast, when injected three hours after methoxamine, isoproterenol had no effect on already elevated levels of enzyme activity. Addition of isoproterenol (10(-7)M), IBMX (1 mM) or dibutyryl cAMP (2.5 mM) to isolated aortic segments cultured in minimal salts-glucose media evoked decreases in basal levels of ODC activity resembling those observed in the intact animal. These results suggest that the balance between alpha and beta adrenergic stimulation may be an important feature of the regulation of polyamine biosynthesis in artery wall cells.