Primary structure of guinea pig plasma prekallikrein

A full length guinea pig plasma prekallikrein (PK) cDNA was cloned from a liver cDNA library. The nucleotide sequence with 2242 bp was analyzed and the amino acid sequence with 618 residues was deduced. Kallikrein was purified from guinea pig plasma and cleavage site in the activation was determined. The amino acid sequence around the cleavage site -368Ile-Asp-Ala-Arg-Ile-Val-Gly-375Gly- differed from that of the human PK -368Thr-Ser-Thr-Arg-Ile-Val-Gly-375Gly-. Protease substrates containing penta-peptides which mimicked the sequence of the cleavage sites from P3 to P2' of guinea pig Hageman factor (HF) and PK were synthesized, and kinetic analyses of the hydrolysis by guinea pig activated HF (HFa) and kallikrein were carried out. The combination between HFa and the PK mimicking peptide provided the best kinetics. These results in part explain why the cascade activation of PK by HFa is predominant in the guinea pig system.     

N-Hydroxylation of 2-aminofluorene in the guinea pig and by guinea pig liver microsomes in vitro

Summary N-hydroxy-2-aminofluorene was found in the urine of guinea pigs intraperitoneally injected with 2-aminofluorene. The hydroxylamine was oxidized to the nitroso analogue and this was identified and determined in the carbon tetrachloride extract by its characteristic UV absorption, by thin-layer chromatography, and by the formation of a diazo compound in the reaction with nitrous acid. Only a small fraction of the 2-aminofluorene injected appeared in the urine as N-hydroxy derivative.Guinea pig liver microsomes were observed to N-hydroxylate 2-aminofluorene rather rapidly, the reaction proceeding at least as rapidly as the N-hydroxylation of aniline.The results of this paper were presented at meetings of the Deutsche Pharmakologische Gesellschaft in Mainz, April 26 to 28, 1965 (Kampffmeyer and Kiese) and Göttingen, September 27 to 30, 1965 (von Jagow, Kiese, Renner, and Wiedemann).     

Apamin and nonadrenergic inhibition of guinea pig trachealis

Apamin has been shown to antagonize the nonadrenergic, noncholinergic (NANC) inhibitory system in guinea pig taenia coli. We have examined the effects of apamin on the nonadrenergic noncholinergic inhibitory system and its putative transmitters in isolated guinea pig trachea. Electrical field stimulation (ES) of isolated trachea pretreated with atropine and propranolol evoked reproducible relaxations that were blocked by tetrodoxin, but were unaffected by apamin. Vasoactive intestinal peptide (VIP), adenosine (AD), and adenosine triphosphate (ATP) produced concentration-dependent inhibition of histamine (H)-induced contractions of isolated trachea but the inhibitory actions of these agents were not significantly affected by apamin. In contrast, apamin virtually abolished ES-evoked relaxations in guinea pig isolated taenia caeci, and reduced the inhibition of H-induced contraction by ATP from 40% to 1%. We conclude that neither the NANC inhibitory system in the guinea pig trachea nor its putative mediators VIP, AD, and ATP are antagonized by apamin, in contrast to taenia caeci.     

Dihydrodiol dehydrogenases in guinea pig liver

Four major and four minor dihydrodiol dehydrogenases, with similar apparent molecular weights of 28,000 to 34,000 but with different charges, were purified from male guinea pig liver cytosol. One of the minor enzymes catalyzed only the oxidation of benzene dihydrodiol with a high Km value of 5.0 mM and was identified immunologically with aldehyde reductase. The other enzymes oxidized xenobiotic alicyclic alcohols and 17 beta-hydroxysteroids as well as benzene dihydrodiol. These enzymes exhibited higher affinity for 17 beta-hydroxysteroids than for alicyclic alcohols and benzene dihydrodiol, and immunologically cross-reacted with testosterone 17 beta-dehydrogenase purified from the same source. Four major enzymes and one minor with Km values for benzene dihydrodiol of about 0.2 mM, possessed specificity for 5 beta-androstane--17 beta-hydroxysteroids and dual cofactor requirement, whereas the other two minor enzymes with high Km values of over 5 mM showed apparent NADP and 5 alpha-androstane specificity. The dihydrodiol dehydrogenase activity was localized in the cytosol of liver. The results indicate that the hepatic oxidation of dihydrodiols in the guinea pig is mediated by cytosolic testosterone 17 beta-dehydrogenase isozymes and aldehyde reductase. Testosterone 17 beta-dehydrogenase immunologically identical to the liver enzymes was detected only in kidney, whereas aldehyde reductase was detected in all tissues of the guinea pig.     

Smooth muscle relaxing drugs and guinea pig ileum

The effects of various smooth muscle relaxing drugs on contractile responses to acetylcholine (ACh), Ba2+ and Ca2+, and on the tissue cyclic AMP levels were examined in the guinea pig ileum. Papaverine and theophylline caused a decrease both in the maximum height and the slope of dose-response curves induced by the three stimulants, and an increase in the cyclic AMP levels. Diltiazem and D-600 produced a decrease in the maximum and the slope of ACh and Ba2+ dose-response curves, shifted the Ca2+ dose-response curves to higher concentrations, in a parallel manner, but failed to change the cyclic AMP levels. Etomidoline and benactyzine shifted the curves for the three stimulants in parallel to the right, but at higher concentrations depressed the maximum of ACh and Ba2+ responses with a further parallel shift. These drugs exerted little influence on the basal level of tissue cyclic AMP, but etomidoline significantly depressed the Ba2+ -induced increase in cyclic AMP level. The smooth muscle relaxing drugs used could be classified in three types, thereby suggesting that there are at least three different mechanisms involved in smooth muscle relaxing action.     

前列腺素E1对豚鼠心室肌细胞ATP敏感K+通道的影响

目的从离子通道水平,探讨前列腺素E1(PGE1)对ATP敏感K+(KATP)通道的作用.方法膜片钳制技术全细胞记录模式.结果PGE1可诱导KATP通道开放并呈浓度依赖关系.保持电位-40mV,指令电位+20mV,持续时间1s条件下,,10μmol·L1PGE1使外向K+电流由给药前的(2.27±0.34)nA增加到(5.46±0.34)nA(n=6,P＜0.01),增加了(3.18±0.23)nA.并且增加的钾电流可被KATP通道特异阻断剂Glibenclamide(10μmol·     

Bromobenzene metabolism in the rat and guinea pig

The metabolism of bromobenzene was studied in the rat and guinea pig with respect to three considerations: the dose and species dependence of 3-bromophenol excretion; the formation of methylthio analogs of dihydrodiols and catechols; and the identification of acidic bivalent sulfur metabolites. In the guinea pig, 3-bromophenol was the major monohydric phenolic metabolite under conditions of both relatively low and relatively high dosage. In the rat, 3-bromophenol and 4-bromophenol were formed in approximately equal amounts. 2-Bromophenol was a minor metabolite in both species. Methylthio analogs of dihydrodiols were found as guinea pig, but not rat, metabolites. Two di(methylthio)dihydroxytetrahydrobromobenzene metabolites were excreted by the rat but not by the guinea pig. These methylthio compounds have not been reported in earlier studies of bromobenzene metabolism. In the guinea pig, the acidic urinary metabolites were a mercaptoacetate, a mercaptolactate, and a mercapturate. In the rat, the acidic metabolites were a mercapturic acid and premercapturic acids. This species difference in urinary acids indicates a difference in acetylation/deacetylation processes for cysteine conjugates.     

Solvent ototoxicity in the rat and guinea pig

There is clear evidence that aromatic solvents can disrupt the auditory system in humans and animals. As far as animal models are concerned, solvent-induced hearing loss seems to be species-dependent. Indeed, most published data have been obtained with the rat, which shows mid-frequency cochlear deficits, whereas the guinea pig does not show any permanent hearing loss after solvent exposure. In the current investigation, the effects of two solvents, toluene (600 ppm) and styrene (1000 ppm), were studied in both Long-Evans rats and pigmented guinea pigs exposed 6 h/day for 5 consecutive days. Cochlear function was tested by using distortion product otoacoustic emissions (DPOAE) measured prior to the solvent exposure, 20 min after the end of the exposure and successively at 2 and 4 weeks post-exposure. In addition to cochlear testing, solvent concentrations in blood and urinary metabolites were measured. A cochlear histological analysis was performed at the end of the experiment. No decrease in DPOAE amplitude was observed in the guinea pig, even immediately following the end of exposure. The rat model showed severe disruption of auditory function and cochlear pathology, whereas the guinea pig had no disruption of DPOAE or cochlear pathological alterations. Therefore, the vulnerability of the cochlear function was strictly dependent on the species. As expected, an important difference in the styrene concentration in blood was observed: the solvent concentrations were fourfold higher in the rat than in the guinea pig. Therefore, it is clear that a pharmacokinetic or an uptake difference might explain the difference in susceptibility observed between the two species. Moreover, the metabolism pathways of the solvents were different depending on the species. Attempts to explain differences of vulnerability between the rat and guinea pig are addressed in the present paper.     

Haloperidol reductase in human and guinea pig livers

A GC assay method for haloperidol reductase was developed. Haloperidol reductase was present in guinea pig liver cytosol as well as in the microsomes, while in human liver only the cytosol exhibited the activity. The reductase activity was NADPH dependent for both species. Known substrates of ketone reductase such as menadione, daunorubicin, and ethacrynic acid strongly inhibited the human haloperidol reductase. The haloperidol reductase showed characteristics of ketone reductase.     

Structure and functions of human kininogens

Evidence has accumulated over the past three decades implicating plasma kininogens in numerous inflammatory processes. Delineation of the detailed biochemistry and, more recently, the molecular biology of the human kininogens has resulted in a deeper understanding of the structure-function correlations of the human kininogens. Studies of alterations of human kininogens in disease states have yielded information about the mechanisms of their involvement in inflammatory states. Here, Raul DeLa Cadena and Robert Colman summarize kininogen function in relation to structure and diagnostic and therapeutic potential.     

Identification of multiple nitrobenzylthioinosine binding sites in guinea pig platelets: Comparison with binding in guinea pig erythrocytes

The novel existence of multiple binding sites for the potent nucleoside transporter Probe, [³H]nitrobenzylthioinosine, was identified in guinea pig platelet membranes and the binding characteristics compared to those of guinea pig erythrocyte membranes. Scatchard analysis of the binding in platelets reveled two high affinity binding sites with affinity constant (K_D) of 0.94 ± 0.07 nM and 83 ± 13 nM with corresponding maximal binding capacities (B_max) of 21 ± 7 and 110 ± 25 fmol/mg protein, respectively. In comparison, guinea pig erythrocyte membranes revealed a homogeneous population of the binding sites with K_D of 0.17 ± 0.04 nM and a B_max value of 73 ± 11 fmol/mg protein. Biphasic semi-log plots of the binding site heterogeneity in erythrocytes not reveled by Scatchard plots. Determination of the potencies of selected drugs in inhibiting the binding showed evidence of differential interacitons with the binding sites by various agents which may be exploited pharmacologically. © 1993 Wiley-Liss, Inc.     

Effects of ATP and VIP on guinea pig airways

The bronchodilator effects of vasoactive intestinal peptide (VIP) and adenosine triphosphate (ATP), putative neurotransmitters of nonadrenergic, noncholinergic innervation, were compared with those of isoproterenol (ISP) in guinea pig airways by in vivo and in vitro techniques. In both studies, the test agents produced dose-dependent relaxations. The response of airway smooth muscle to ISP was significantly greater than the responses to the test agents. In the in vivo studies, the test agents produced statistically equieffective responses. However, in the in vitro studies, VIP produced complete relaxation of the precontracted tissues to the baseline, whereas ATP could not, suggesting VIP as a more effective relaxant than ATP.     

HPLC法测定豚鼠血浆中甲泼尼龙的含量

目的建立豚鼠血浆中甲泼尼龙的含量测定法。方法应用HPLC法测定甲泼尼龙的含量。HPLC色谱条件为:ZORBAXEclipse XDB-C18色谱柱(250 mm×4.6 mm,5μm),流动相为7.56 mmol.L-1硫酸铵-乙腈(68∶32,V/V),流速1.0 mL.min-1,柱温20℃,检测波长243 nm。结果甲泼尼龙的线性范围为0.10~5.0 mg.L-1(r=0.999 8),最低检测限为0.04 mg.L-1,日内和日间RSD分别为1.91%和2.57%,给药后2 h血浆的质量浓度为1.67 mg.L-1。结论本方法灵敏、准确、重现性好,可用于血浆中甲泼尼龙的测定。     

Fentanyl-induced airway hyperreactivity in the guinea pig

The bronchopulmonary effects of fentanyl were studied in mechanically ventilated, paralyzed guinea pigs that had been anaesthetized with pentobarbitone sodium. Fentanyl did not alter the resting bronchial tone but enhanced the bronchoconstrictor effects of 5-hydroxytryptamine in a dose-related manner. The enhancement induced by 20 micrograms kg-1 fentanyl was suppressed by pretreatments with 0.5 mg kg-1 naloxone or 5 mg kg-1 propranolol, but did not change after 3 mg kg-1 atropine. The bronchoconstrictor responses to histamine were also enhanced by 20 micrograms kg-1 fentanyl. These results suggest that fentanyl-induced airway hyperreactivity is not mediated by an increase in vagal tone but is due to a reduction in the central sympathetic drive and/or in the levels of circulating catecholamines, which occurs through stimulation of opiate receptors.     

MAO types in guinea pig liver mitochondria

MAO of guinea pig liver mitochondria actively deaminated dopamine, tyramine, serotonin and 5-methoxy-tryptamine, while tryptamine, 5-methyl-tryptamine and 7-methyl-tryptamine were moderately deaminated. Very little deamination occurred when benzylamine. noradrenaline and β-phenylethylamine were used as substrates. The in vitro inhibition patterns of MAO of guinea pig liver mitochondria by some selective inhibitors were investigated in the presence of tyramine, tryptamine and serotonin. Tryptamine oxidation showed biphasic inhibition pattern with harmaline, clorgyline and Lilly 51641, while the inhibition curves in the presence of pargyline and deprenyl were sigmoidal. The inhibition curves for tyramine oxidation were biphasic with all the inhibitors except pargyline. Serotonin-MAO inhibition curves, on the other hand, were sigmoidal with all the inhibitors except Lilly 51641. Thermal treatment of guinea pig liver mitochondria produced rapid inactivation of serotonin and tryptamine oxidizing activity, while benzylamine oxidizing activity was found to be most thermostable.