Rat paw oedema and mast cell degranulation caused by two phospholipase A2 enzymes isolated from Trimeresurus mucrosquamatus venom

Two phospholipase A2 (PLA2) enzymes, TMVPLA2 I and TMVPLA2 II, isolated from Trimeresurus mucrosquamatus venom (TMV) induce rat hind-paw oedema in a dose-dependent manner. This response is suppressed by pretreatment with diphenhydramine, methysergide or compound 48/80, which reduces tissue histamine content. In isolated mast cells, TMVPLA2 I and TMVPLA2 II cause concentration-, time- and calcium-dependent release of histamine and beta-glucuronidase. This effect is inhibited by disodium cromoglycate, mepacrine, nordihydroguaiaretic acid, piriprost and BW 755C, but not by aspirin or indomethacin. These observations indicate that the mast cell plays a predominant role in TMVPLA2 I- and TMVPLA2 II-induced paw oedema, and that venom PLA2 enzyme needs an intact lipoxygenase pathway to induce mast cell degranulation.

Comparison of the enzymatic and edema-producing activities of two venom phospholipase A2 enzymes

The edema-producing activity of NNAVPLA2, an acidic phospholipase A2 (PLA2) enzyme from Naja naja atra venom (NNAV), was less potent than that of TMVPLA2 II, a basic PLA2 from Trimeresurus mucrosquamatus venom (TMV). These edema-forming effects were greatly suppressed by pretreatment of rats with diphenhydramine/methysergide or compound 48/80, which reduced the tissue content of histamine and serotonin. Heparin abolished and suppressed the paw edema caused by protamine and TMVPLA2 II, respectively, but had no effect on the NNAVPLA2-induced response. In isolated rat peritoneal mast cells, both PLA2 concentration dependently induced the release of histamine and beta-glucuronidase. Again, TMVPLA2 II was more potent than NNAVPLA2. This degranulation effect of mast cells caused by TMVPLA2 II and protamine was inhibited by heparin, while that caused by NNAVPLA2 was unaffected. The edema-forming and mast cell degranulation effects were greatly decreased in both PBPB-modified NNAVPLA2 and PBPB-modified TMVPLA2 II, in which the catalytic activity of the enzymes was completely lost. PBPB-modified TMVPLA2 II-induced paw edema was also suppressed by heparin. Furthermore, this edematous response was totally reversed in rat pretreated with aspirin in combination with diphenhydramine and methysergide. These results suggest that the edema-forming effect of PLA2 is probably dependent on the presence of catalytic, positive charge and pharmacological sites on its molecule.

[The distribution, characteristics and effects of ir-BNP in central and peripheral tissues in rat]

The present study first investigated the distribution, biochemical characteristics, receptor binding and biological effects of immunoreactive brain natriuretic peptide (ir-BNP), in the central nervous system and some peripheral tissues in rats, using highly specific radioimmunoassay, radioreceptor assay and immunohistochemical method. The results suggest that BNP may be a novel neurotransmitter or circulatory hormone, which is widely distributed in various tissues and involved in the regulation of water electrolyte balance and cardiovascular activity.

[Distribution of substance K in the rat heart and its cardiovascular effects]

The present work was to investigate the distribution of Substance K (SK) in the rat heart and its cardiovascular effects. The content of SK-like immunoreactive material (SKLI), determined by using specific radioimmunoassay, was higher in the atrium (19.9 +/- 3.5 pmol/g tissue) than in the ventricle (4.1 +/- 0.8 pmol/g tissue). SKLI in the heart existed in the nerves fibers and its molecular form was identical with synthetic SK. There were high affinity binding sites of SK on the cardiohybricyte CP 8401: KD = 0.161 nmol/L, Bmax = 8.08 pmol/L. SK stimulated the release of ANF from the cardiohybricytes and from the isolated rat atria. Furthermore, SK injected intravenously induced a hypotensive effect in rats, and decreased left ventricle end systolic pressure (LVESP), +/- LVdp/dtmax, as well as slightly increased heart rate (HR). In isolated Langendorff perfusion heart of rat, SK increased HR, LVdp/dtmax, left ventricle peak systolic pressure (LVPSP) and perfusion pressure (PP). These effects of SK were inhibited by a tachykinin receptor antagonist, (D-Pro2, D-Trp7.9)-SP. These findings suggest that SK exist in the heart and might be able to bind with its specific binding sites on the cardiocytes, thus inducing the release of ANF from the atrium and regulating cardiovascular functions.

[Calcitonin gene-related peptide in normotensive and spontaneously hypertensive rats]

Using specific radioimmunoassay, radioimmunoreceptor analysis and gel filtration, we found that calcitonin gene-related peptides (CGRP) were distributed in various tissues of normotensive rat (WKY) and spontaneously hypertensive rat (SHR), the highest content was in the lumbar spinal cord (1197 +/- 94.8 pg/mg tissue), the lowest in the auricle (15.0 +/- 2.1 pg/mg tissue). Compared with WKY, the plasma CGRP concentration decreased and the CGRP content in abdominal aorta and hypothalamus increased in SHR. By gel filtration, it showed that only one major molecular form of CGRP was present in the tissues. The CGRP specific binding sites were present both in SHR and WKY hearts, but the number of CGRP binding sites in SHR heart was higher and the binding affinity lower than those in WKY heart. Besides, CGRP can reduce the mean arterial pressure (MAP) in the SHR in a dose-dependent way. The above data indicated that CGRP may play an important role in the pathogenesis of hypertension and exert possibly a therapeutic effect on hypertension.

Calcitonin gene-related peptide (CGRP) in normotensive and spontaneously hypertensive rats

With the techniques of specific radioimmunoassay and gel filtration it was found that CGRP was distributed in various tissues of normotensive (WKY) and spontaneously hypertensive rats (SHR) with the highest concentration in the lumbar spinal cord (1197 +/- 94.8 pg/mg tissue) and the lowest in the auricle (15.0 +/- 2.1 pg/mg tissue). In comparison with WKY, CGRP concentration in the plasma was decreased and in the abdominal aorta and hypothalamus was increased in SHR. Gel filtration revealed only one major CGRP molecular form in the tissues. In addition, CGRP reduced the mean arterial pressure (MAP) in SHR in a dose-dependent manner. These data suggest that CGRP may play an important role in the pathogenesis of hypertension and its possible therapy.

Edematous response caused by [Thi5,8,D-Phe7]bradykinin, a B2 receptor antagonist, is due to mast cell degranulation

[Thi5,8,D-Phe7]bradykinin caused hind-paw edema and degranulation of isolated peritoneal mast cells in a dose-dependent manner. Pretreatment with diphenhydramine/methysergide or compound 48/80 completely suppressed the edematous response caused by [Thi5,8,D-Phe7]bradykinin, whereas bradykinin-induced hind-paw swelling was only partially inhibited by diphenhydramine and methysergide pretreatment; the residual response was significantly further depressed by [Thi5,8,D-Phe7]bradykinin. Neither the bradykinin- nor [Thi5,8,D-Phe7]bradykinin-induced edematous response was significantly affected by aspirin or BW755C. The mast cell degranulation caused by [Thi5,8,D-Phe7]bradykinin and bradykinin was inhibited by gangliosides but not by heparin. These results suggest that the edematous response elicited by [Thi5,8,D-Phe7]bradykinin was mainly due to the actions of mediators released by the degranulation of mast cells. Unlike bradykinin, [Thi5,8,D-Phe7]bradykinin was devoid of a direct exudation-promoting effect but exerted an antagonistic effect on the direct effect of kinin. If the influence of mast cells degranulation could be minimized, [Thi5,8,D-Phe7]bradykinin could be used as a tool to evaluate the role of kinin in the edematous response in inflammation.

Roles of mast cells and PMN leukocytes in cardiotoxin-induced rat paw edema

Cardiotoxin, isolated from the venom of Naja naja atra, was found to cause rat hind-paw edema in a dose-dependent manner. This edematous response was significantly suppressed by pretreatment with diphenhydramine, methysergide or compound 48/80, which reduced the tissue histamine content. Polymorphonuclear (PMN) leukocyte infiltration appeared within 1 h and had accumulated markedly in the rat paw 3-6 h after subplantar injection of cardiotoxin. Methotrexate pretreatment significantly reduced not only the peripheral leukocyte count but also cardiotoxin-induced paw edema. Captopril, a kininase inhibitor, potentiated the edematous response caused by a low dose of cardiotoxin. The initial phase, occurring within 3 h, of paw edema induced by cardiotoxin was suppressed by trasylol, [Thi5,8,D-Phe7]bradykinin, or by cellulose sulfate pretreatment which greatly reduced plasma kininogen levels. Both mast cells and PMN leukocytes possess kinin-forming activities, but with different properties. The kinin-forming activity of mast cells but not of PMN leukocytes was inhibited by trasylol. In isolated mast cells, cardiotoxin caused a dose-dependent release of histamine, beta-glucuronidase, lactate dehydrogenase and kinin-forming activity. These observations suggest that mast cells and PMN leukocytes are involved in cardiotoxin-induced paw edema, and that inflammatory mediators such as histamine, serotonin and kinins were supplied directly or indirectly by mast cells, at least in the initial phase.

[Atrial natriuretic polypeptide in the human and rat spinal cord]

The widespread distribution of atrial natriuretic polypeptide (ANP) immunoreactive material was demonstrated in the human and rat spinal cord, using specific immunogold-silver staining technique and radioimmunoassay. Immunogold-silver staining studies showed that ANP immunoreactive neurons were quite prevalent in the human spinal cord. ANP immunoreactive neurons were largely found in the ventral horn and less in the dorsal and lateral horns. ANP immunoreactive material was absent with anti-ANP serum preabsorbed with ANP. In rats, radioimmunoassay demonstrated that ANP immunoreactive material was present in whole spinal cord. The highest concentration was found in the sacral spinal cord (21.9 +/- 4.48 ng/g tissue), the moderate in the lumbar (3.78 +/- 0.74 ng/g tissue) and the lowest in the cervical and thoracic (0.58 +/- 0.14 and 0.46 +/- 0.21 ng/g tissue, respectively). Gel chromatography and reverse-phase HPLC revealed multiple molecular forms in the rat spinal cord, but the main molecular form was the 28 amino acid rANP. In vivo study showed that ANP was released from the rat spinal cord by depolarizing concentration of potassium.

Retinal projections to the medial terminal nucleus of the rat with induced unilateral congenital eye defects

Retinal projections, particularly the ipsilateral projections, to the medial terminal nucleus (MTN) of the accessory optic system were investigated by autoradiography in adult rats after being reared in one of three different conditions: (1) normal visual experiences, (2) an application of trypan blue for intrauterine induction of congenital unilateral anophthalmia; and (3) the procedures for intrauterine production of congenital microphthalmia in which both eyes are reduced in size. In congenital monocular rats, there was an increase of uncrossed retinal projections to the MTN which does not normally exist. The expansion of the ipsilateral projection was markedly greater in the monocular rats than those inflicted with microphthalmia. The expansion may be due to the failure of the retraction of the ipsilateral retinal projections to the MTN and the collateral sprouting of optic fibers from the remaining eye.

Edema-producing proteins isolated from Trimeresurus mucrosquamatus snake venom

Seven edema-producing fractions were isolated from Trimeresurus mucrosquamatus snake venom by CM-Sephadex C-50 chromatography and further purified by gel filtration on a Sephadex G-75 column. They were homogeneous as judged by electrophoresis on polyacrylamide gels. The mol. wts were estimated to be 26,900 (Fr. IV-2), 21,500 (Fr. X-2), 23,000 (Fr. XII-2), 21,800 (Fr. XIII-2), 24,600 (Fr. XIV-2), 80,000 (Fr. XVIII-1) and 22,500 (Fr. XXII-2). Fraction IV-2 had weak esterase activity, fractions X-2, XII-2, XIII-2 and XIV-2 possessed proteolytic activity toward casein and fibrinogen, while fractions XVIII-1 and XXII-2 possessed phospholipase A2 activity. Fractions with phospholipase A2 activity had greater edema-producing activity than those with protease and/or esterase activity. It is concluded that the edema caused by T. mucrosquamatus venom may be due to phospholipases A2, proteases and esterases.

Effects of venom proteases on peptide chromogenic substrates and bovine prothrombin

Eighteen proteases were isolated from six hemorrhagic venoms of snakes belonging to the families of Crotalidae and Viperidae. According to their actions, they are classified as thrombin-like enzymes, alpha-fibrinogenases, beta-fibrinogenases, Factor X activator, prothrombin activator, hemorrhagins and esterases. Thrombin-like enzymes, beta-fibrinogenases, hemorrhagins and esterase hydrolyzed Phe-Pip-Arg-pNA (S-2238, substrate for thrombin) more strongly than CBZ-Ile-Glu-Gly-Arg-pNA (S-2222, substrate for Factor Xa), CBZ-Phe-Val-Arg-pNA (B-7632) or CBZ-Pro-Phe-Arg-pNA (B-2133). Thrombin-like enzymes, beta-fibrinogenase and esterase hydrolyzed tosyl-L-arginine methyl ester and benzoyl-L-arginine ethyl ester. S-2238 is the most susceptible chromogenic substrate for most venom proteases. Thrombin-like enzymes degraded prothrombin molecule progressively down to prethrombin 2 while alpha- and beta-fibrinogenases degraded it only to prethrombin 1. Factor X activator of Vipera russelli venom and esterase of T. mucrosquamatus venom did not have any effect on prothrombin. Thus, the effects of venom proteases on prothrombin are not parallel to their amidolytic or esterolytic effects.

Rat paw edema induced by trimucase II, a kinin-releasing enzyme from Trimeresurus mucrosquamatus venom

Trimucase II, a proteolytic enzyme isolated from Trimeresurus mucrosquamatus venom, caused rat hind-paw edema dose dependently. Captopril potentiated significantly, while pretreatment with cellulose sulfate suppressed the trimucase II-induced edematous response. Pretreatment with diphenhydramine and methysergide reduced by 42 and 46% the edema induced by trimucase II and kallikrein, respectively. The residual response was significantly further depressed by [Thi5,8,D-Phe7]bradykinin and trasylol. Kinin generation by trimucase II was also found in vitro from plasma and was concentration- and time-dependent. Kinin formation was inhibited by soybean trypsin inhibitor, trasylol and endogenous kininase. The kinins released were destroyed by chymotrypsin. Unlike cellulose sulfate, trimucase II caused kinin formation from Factor XII-deficient and prekallikrein-deficient plasma but not from high molecular weight kininogen-deficient plasma. These data indicate that, in addition to the mediators released from mast cells, kinins have an important role in the edema caused by trimucase II, and that kinins are released from plasma, probably due to direct activation of kininogen.

[Alpha-hANP-like immunoreactivity in lung cancer]

Specific radioimmunoassay and immunohistochemical method of alpha-human atrial natriuretic polypeptide (alpha-hANP) was established to diagnose one case of large cell lung carcinoma (clear cell carcinoma) proved by pathology. It was found that there was alpha-hANP-like immunoreactivity in the cancer cells at a concentration of 147.5 pg/mg protein. Chromatography analysis showed that alpha-hANP-like immunoreactive materials had multiple molecular forms. The significance of these phenomena remains to be further investigated.

The effect of vasopressor agents upon uterine artery blood flow velocity in the gravid guinea pig subjected to ritodrine infusion

The purpose of the present study was to assess the effects of intravenously administered vasopressors upon uterine artery blood flow velocity (UBFV) in the gravid guinea pig subjected to ritodrine infusion. Fourteen experiments were performed in 14 chronically instrumented pregnant guinea pigs near term. Immediately following a 1-h intravenous infusion of ritodrine (0.05-0.20 mg.kg.min-1), each animal received an intravenous bolus of vasopressor solution: 1) epinephrine, 0.001 mg/kg; 2) phenylephrine, 0.01 mg/kg; 3) mephentermine, 1.0 mg/kg; 4) ephedrine, 1.0 mg/kg; or 5) placebo. The experimental sequence was performed five times, so that each animal received all five solutions. The vasopressor sequence was randomly altered between animals. Infusion of ritodrine increased maternal heart rate 18 +/- 1% (P less than .0001), decreased maternal mean arterial pressure (MMAP) 4 +/- 1% (P less than .01), and decreased UBFV 5 +/- 1% (P less than .001). The four active vasopressor solutions resulted in similar, though not equivalent, increases in MMAP. Further, the MMAP response to each active vasopressor differed from the response to placebo (P less than .0001). Epinephrine and phenylephrine each significantly decreased UBFV (P less than .002). Ephedrine clearly preserved UBFV, whereas mephentermine appeared to result in an intermediate response.

[Colonic cancer induced by 1,2-dimethylhydrazine (DMH) in rats after partial colectomy]

Using colonic cancer induced by DMH as experimental model, carcinogenic rate in the rats with or without partial colectomy was compared in order to study the etiology of the local recurrence of large bowel cancer after radical resection and observe the influence of operative injury on carcinogenesis. Sixty five male Wistar rats were divided into two groups: 48 with a partial colectomy (group 1) and 17 controls (group 2). All were given subcutaneous injection of DMH 20 mg/kg weekly for twenty weeks. Then, some rats were killed on scheduled time, the others were sacrificed in the 29th week. The results showed that carcinogenic rate was 87.5% and 58.8% in groups 1 and 2 (P less than 0.05). The tumor number in anastomotic site in group 1 (57.1%) was much higher than that at corresponding site in group 2 (28.6%) (P less than 0.05). It is suggested that the trauma itself be one of the promoting factors for cancer recurrence in addition to implantation during operation, residual tumor, etc. Large bowel cancer induced by DMH in rats may be used as an experimental model in studying the same cancer in the human being. Furthermore, after having given DMH, large bowel cancer incidence of the rats in different intervals is described.

The effect of ephedrine upon uterine artery blood flow velocity in the pregnant guinea pig subjected to terbutaline infusion and acute hemorrhage

The purpose of the present study was to determine the effect of intravenously administered ephedrine upon uterine artery blood flow velocity (UBFV) in the gravid guinea pig subjected to terbutaline infusion and acute hemorrhage. Ephedrine, 1.0 mg/kg, was administered intravenously to ten chronically instrumented pregnant guinea pigs near term, before and after intravenous infusion of terbutaline and acute hemorrhage. Before terbutaline and hemorrhage, ephedrine increased maternal mean arterial pressure (MMAP) by 30 +/- 1% (P = .0001) and 17 +/- 1% (P = .0001) at 30 s and at 1 min after injection, respectively; UBFV was decreased by 10 +/- 4% (P less than .01) and 14 +/- 4% (P less than .01) at 1 min and at 90 s after injection, respectively. Infusion of terbutaline (1.5-6.0 ug X kg-1 X min-1) increased maternal heart rate (MHR) by 22 +/- 1% (P = .0001), decreased MMAP by 13 +/- 2% (P = .0001), and decreased UBFV by 24 +/- 3% (P = .0001). During hypotension resulting from acute hemorrhage, ephedrine, 1.0 mg/kg, was superior to placebo in restoring MMAP and UBFV toward the prebleed values. The authors concluded that ephedrine, 1.0 mg/kg, results in a small, transient decrease in UBFV in the normotensive gravid guinea pig. However, ephedrine aids restoration of UBFV in the gravid guinea pig rendered hypotensive by acute hemorrhage during terbutaline infusion.

The interaction between serotonin and angiotensin II in the chronically instrumented guinea pig and its alteration by indomethacin

We examined the effect of a subthreshold infusion of serotonin on the angiotensin II pressor response in the chronically instrumented pregnant and nonpregnant guinea pig before and after administration of a prostaglandin synthesis inhibitor. Arterial blood pressure was significantly lower in the pregnant animal (p = 0.0135). An infusion of serotonin, which failed to alter the blood pressure, pulse, or uterine artery flow velocity, significantly increased the pressor response to angiotensin II infused at 3.5, 7.5, 14.5, and 29 ng/kg/min in both the pregnant (p = 0.0001) and, to a lesser degree, the nonpregnant animal (p = 0.004). Pretreatment with indomethacin heightened the angiotensin pressor effect significantly in the pregnant group (p = 0.0001) and to a near-significant degree in the nonpregnant group (p = 0.074). However, indomethacin enhanced the angiotensin II-serotonin synergism only in the pregnant animal (p = 0.0008). The angiotensin II-serotonin synergism persisted after pretreatment with the sympathetic blocking agent bretylium tosylate. We concluded that serotonin augments the pressor effect of angiotensin II in the pregnant and nonpregnant guinea pig; however, this synergism is potentiated by the inhibition of prostaglandin synthesis only in the pregnant animal.

Effect of hsien-ho-t'sao (Agrimonia pilosa) on experimental thrombosis in mice

The water extract of Hsien-Ho-T'sao (HHT) prolonged the tail bleeding time in conscious mice. This antihemostatic effect was dose-dependent and exhibited a biphasic pattern; i.e. its activity declined at doses higher than 0.5 mg/kg. the prolonged bleeding time persisted for at least 12 hr and maximal effect was observed at 3 hr after the oral administration of HHT 500 mg/kg. HHT was effective in preventing ADP-induced acute pulmonary thromboembolic death in mice, while aspirin and indomethacin had no effect on this model. HHT, like aspirin and indomethacin, also reduced the mortality in collagen- and sodium arachidonate-induced thromboembolic death. All three drugs caused no significant protection in endotoxin shock. HHT was found to suppress platelet aggregation markedly, but little effect on blood coagulation. In conclusion, HHT was proved to be effective in the treatment of acute pulmonary thromboembolism, and this effect was mainly due to its antiplatelet action.