Synthesis of P-Stereogenic Phosphinamides via Pd(II)-Catalyzed Enantioselective C-H Alkynylation

P-Stereogenic phosphinamides represent important structural elements in chiral organocatalysts and bioactive compounds. Herein, we report Pd(II)-catalyzed enantioselective C-H alkynylation using cheap commercially available l-pyroglutamic acid as a chiral ligand. A range of structurally diverse P-stereogenic phosphinamides was prepared in good yields with high enantioselectivities via desymmetrization and kinetic resolution. A tailor-made congested directing group, N-ethyl-N-(3-methylpyridin-2-yl)amino, was crucial for the reactivity.

[Screening of differently expressed miRNAs and the mechanism of miR-3907 in meibomian gland carcinoma]

Objective: To screen the differently expressed microRNAs (miRNAs) and to explore the effect and mechanism of microRNA-3907 (miR-3907) in meibomian gland carcinoma (MGC). Methods: Experimental research. MGC tissues and para-carcinoma tissues of patients diagnosed with MGC by histopathology were collected from July 2011 to January 2019 in Tianjin Medical University Eye Hospital. The miRNA microarray analysis of MGC and para-carcinoma tissue samples from 5 patients was performed. miR-3907 with a significant up-regulation was selected as a research object. Bioinformatics predicted and dual-luciferase gene reporter assay verified miR-3907 target genes. The protein expression levels of target genes in 18 MGC tissues and 6 para-carcinoma tissue samples were determined by immunohistochemical staining. miR-3907 over-expression, miR-3907 knock-down, target gene knock-down and miR-3907 knock-down with target gene knock-down were respectively performed in MGC cell. The mRNA and protein expressions were validated by real-time PCR and Western blotting after transfection. The cell proliferation and migration ability was detected by cell counting kit-8 and scratch experiment after transfection. The main statistical methods were Fisher's exact test, independent sample t test, two-factor repeated measure analysis of variance. Results: There were 22 differently up-regulated miRNAs and 5 differently down-regulated miRNAs in MGC tissues, of which miR-3907 was significantly up-regulated. Thrombospondin-1 (THBS1) was a target gene of miR-3907 according to bioinformatics and dual-luciferase gene reporter assay. The positive expression rate of THBS1 protein in para-carcinoma tissues (6/6) was significantly higher than that in MGC tissues (5/18), and the difference was statistically significant (P=0.003). Compared with the negative control group, the proliferation ability of the miR-3907 over-expression group was increased at 48 h and 72 h (F=3.70, 2.65; both P<0.01), and the migration rate at 24 h was significantly higher (54.6%±3.4% vs. 34.2%±0.6%; t=8.34, P<0.01). Compared with the negative control group, the proliferation ability of the miR-3907 knock-down group was decreased at 24 h, 48 h and 72 h (F=3.10, 2.17, 3.09; all P<0.05), and the migration rate at 24 h was significantly lower (40.8%±2.8% vs. 69.7%±2.7%; t=10.42, P<0.01). Compared with the negative control group, the THBS1 knock-down group promoted cell proliferation at 24 h, 48 h and 72 h (F=3.84, 3.79, 2.24; all P<0.05), and the migration rate at 24 h was significantly increased (82.5%±1.9% vs. 37.6%±5.1%; t=11.74, P<0.01). Compared with the control group, the miR-3907 knock-down with THBS1 knock-down group increased proliferation at 24 h and 48 h (F=3.97, 3.31; both P<0.05), and the migration healing rate at 24 h was significantly increased (56.9%±2.2% vs. 41.9%±4.3%; t=3.53, P<0.05). Conclusions: There are differently expressed miRNAs between MGC and para-carcinoma tissues, which may be related to the occurrence and development of MGC. miR-3907 in MGC tissues has a significant difference from that in para-carcinoma tissues. Moreover, miR-3907 can play a role in promoting proliferation and migration of MGC by inhibiting the expression of THBS1.

Synthesis of Chiral Sulfoxides via Pd(II)-Catalyzed Enantioselective C-H Alkynylation/Kinetic Resolution of 2-(Arylsulfinyl)pyridines

A Pd(II)-catalyzed enantioselective C-H alkynylation of 2-(arylsulfinyl)pyridines via kinetic resolution using cheap and commercially available l-pGlu-OH as a chiral ligand is reported. A wide range of 2-(arylsulfinyl)pyridines were compatible with this protocol, giving the alkynylation products and recovered sulfoxides in high yields with high enantioselectivities (up to 99% ee). Furthermore, the enantioenriched products can be easily transformed to several other types of chiral sulfoxide scaffolds with the retention of enantiopurity.

[Proteomic analysis of lacrimal gland adenoid cystic carcinoma with high-grade transformation]

Objective: To analyze the protein expression differences of lacrimal gland adenoid cystic carcinoma (LACC) with high-grade transformation (HGT). Methods: Experimental study. A total of 8 paraffin tissue samples were collected in Tianjin Medical University Eye Hospital from December 2012 to January 2019. According to pathological examination, the samples were divided into the LACC group and the LACC-HGT group, with 4 cases in each group. The LACC group included 2 male samples and 2 female samples, with an average age of 53 years. The LACC-HGT group included 2 male samples and 2 female samples, with an average age of 44 years. Primary cells were cultured from fresh tumor tissue. Isobaric tags for relative and absolute quantification techniques were used to screen the differentially expressed proteins between the two groups, and bioinformatics analysis was conducted for the differentially expressed proteins. Microarray was used to screen differentially expressed mRNAs between LACC and LACC-HGT primary cells. The mass spectrum data were intersected with mRNA microarray data, and quantitative real-time (qRT) PCR was performed to verify the results. Proteomics and microarray data were compared using the independent sample t test. The qRT-PCR data were compared pairwise by one-way analysis of variance. Results: A total of 105 HGT-related differential proteins were detected in this study, including 50 up-regulated proteins and 55 down-regulated proteins. The significantly up-regulated proteins included hemoglobin subunit beta, hemoglobin subunit alpha 1, and collagen type Ⅵ alpha 2 chain; the significantly down-regulated proteins included Cereblon, adenosylhomocysteinase like 2, and ribosomal protein L39 pseudogene 5. Gene ontology analysis results showed that the LACC-HGT differential proteins were mainly located in the cytoplasm, vesicle cavity, and extracellular matrix, had organic acid binding and molecular carrier activity, and participated in the regulation of extracellular matrix composition, immunity, inflammation, apoptosis, and other biological processes. Pathway analysis showed that the LACC-HGT differential proteins were mainly involved in signal pathways such as mitogen-activated protein kinase signal pathway and extracellular matrix proteoglycans and glycan metabolism signal pathway. Protein complex prediction analysis screened out 4 up-regulated protein complexes and 1 down-regulated protein complex. There were 15 LACC-HGT differential proteins that overlapped with mRNA chip differential genes, of which 6 were tumor-related proteins including collagen type XIV alpha 1 chain (COL14A1), EMAP like 4 (EML4), inter-alpha-trypsin inhibitor heavy chain 4 (ITIH4), NDRG family member 2 (NDRG2), osteoglycin (OGN) an Ras homolog family member C (RhoC). The main function was the movement and migration of tumor cells. The qRT-PCR results showed that the relative expression levels of COL14A1, EML4, ITIH4, NDRG2, OGN, and RhoC in primary LACC-1, LACC-2, LACC-HGT-1, and LACC-HGT-2 cells were significantly different (F=1 675.98, 38.53, 27.37, 16.47, 13.38, 25.22, all P<0.01). For example, the relative expression of COL14A1 in primary LACC-HGT-1 (16.09±0.51) and LACC-HGT-2 (9.96±0.34) cells was significantly higher than that in primary LACC-1 (1.00±0.13) and LACC-2 (0.67±0.08) cells (all P<0.05). Conclusion: There are differentially expressed proteins between LACC-HGT and LACC, among which COL14A1, EML4, ITIH4, NDRG2, OGN, and RhoC may play an important role in LACC-HGT and can be used as potential targets of LACC-HGT in further study. (Chin J Ophthalmol, 2021, 57: 531-539).

Pd(II)-Catalyzed enantioselective arylation of unbiased methylene C(sp3)-H bonds enabled by a 3,3'-F2-BINOL ligand

Palladium-catalyzed asymmetric functionalization of unbiased methylene C(sp3)-H bonds is a long-standing challenge. Here, we report a Pd(ii)-catalyzed highly enantioselective arylation of unbiased methylene C(sp3)-H bonds enabled by a strongly coordinating bidentate 2-pyridinylisopropyl (PIP) directing group and an easily accessible 3,3'-F2-BINOL chiral ligand. The use of aryl iodides with the combination of 3,3'-F2-BINOL was beneficial for high enantiocontrol. A range of aliphatic amides and aryl iodides were tolerated, providing the desired arylated products in high enantioselectivities (up to 96% ee). The PIP directing group could be removed under mild conditions without erosion of enantiopurity.

Pd(ii)-Catalyzed asymmetric intramolecular arylation of unbiased methylene C(sp3)–H bonds using readily accessible 3,3′-F2-BINOL as a chiral ligand

Pd(ii)-Catalyzed asymmetric intramolecular methylene C(sp³)–H arylation using readily accessible 3,3′-F₂-BINOL as a ligand is reported.

Late-stage functionalization of peptides via a palladium-catalyzed C(sp3)–H activation strategy

Recent advances in the late-stage modification of peptides via palladium-catalyzed C(sp³)–H functionalization are summarized.

[FOXD2-AS1 is corelated with clinicopathological parameter of laryngeal carcinoma and promote cancer cell proliferation]

Objective: To investigate the expression and clinical significance of long non-coding RNA FOXD2-AS1 in laryngeal squamous cell carcinoma and its effect on cancer cell proliferation. Method: Real-time quantitative polymerase chain reaction(RT-qPCR) was used to detect the expression of FOXD2-AS1 in 85 cases of laryngeal carcinoma. One-way ANOVA was used to determine relationships between its expression and clinicopathological parameters of laryngeal carcinoma. The prognostic significance of FOXD2-AS1 in head and neck cancer was explored using bioinformatics technology. SiRNA was used to interfere the expression of FOXD2-AS1 in TU686 laryngeal carcinoma cells. MTT and clonal formation assay were used to investigate the biological effect of FOXD2-AS1. MicroRNA binding to FOXD2-AS1 was investigated using double luciferase assay. Result: The expression of FOXD2-AS1 in laryngeal cancer tissues was significantly higher than that in normal tissues(t=10.012, P<0.05), and was associated with T staging of laryngeal cancer(χ=6.41, P=0.016). There were no relationships between FOXD2-AS1 expression and age, sex, smoking history, primary site of tumor and lymph node metastasis(N staging). Survival analysis of head and neck tumors in the TCGA database using GEPIA showed poor prognosis in patients with high FOXD2-AS1 expression(P=0.048). Suppressing FOXD2-AS1 via siRNA in TU686 cells decreased clonal formation ability(t=8.053, P<0.05) and MTT assay confirmed that interference of FOXD2-AS1 down regulated proliferation activity of TU686 cells(t=9.337, P<0.05). Double luciferase assay showed that FOXD2-AS1 could directly bind to miR-206, thus inhibiting the expression of miR-206. Further MTT assay indicated that inhibiting miR-206 attenuated the suppressing effect of si-FOXD2-AS1 on the proliferation of TU686 cells. Conclusion: FOXD2-AS1 is corelated with clinicopathological parameter of laryngeal squamous cell carcinoma and promotes cancer cell proliferation through targeting miR-206.

Scalable Formal Synthesis of (-)-Quinocarcin

A scalable and unified strategy is described for the synthesis of (-)-quinocarcin, an important tetrahydroisoquinoline antitumor alkaloid. The strategy allows the practical formal synthesis of (-)-quinocarcin in 13 steps and 4.8% overall yield using N-phthaloyl-l-alanine as a chiral pool. It features the gram-scale and stereoselective synthesis of the tetrahydroisoquinoline moiety (AB ring) via Pd-catalyzed C(sp³)-H arylation and Pictet-Spengler condensation and a Cu(I)-catalyzed exo-selective [C + NC + CC] coupling reaction to generate the chiral pyrrolidine motif (D ring).

[Inflammatory myofibroblastic tumor: a case report]

A 59 years old woman with chief complain of intermittent hemoptysis and shortness of breath was admitted to our hospital. Fiberoptic laryngoscope: no abnormality seen; enhanced computerized tomography of the neck showed that at the second trachea ring located a round nodule with a diameter of about 23 mm, flat on the sixth cervical vertebrae, consider vascular tumors. The immunohistochemistry: an inflammatory myofibroblastic tumor.

Comparison of laparoscopy and open surgery in treating severe acute pancreatitis and its relative aftercare

This study was designed to determine the effects and compare laparoscopic intervention and open surgery in treating severe acute pancreatitis (SAP) and its relative aftercare, to improve the overall treatment of SAP. Ninety patients with SAP were enrolled from the 2nd Affiliated Hospital of Harbin Medical University from 2008 to 2014 and divided into a laparoscopic intervention group (25 cases) and an open surgery group (65 cases). Patients were asked for clinical symptoms, general hospital information, laboratory inspection, imageological examination, local and systemic complications, treatment and outcome. SAP patients’ relevant clinical indicators were compared between the two groups before and after the operation. Results revealed that there was no statistical significance in lesion range and main scoring indexes for reflecting the severity of the disease. For both groups statistical significance was found in blood loss (285.3±79.8 mL vs 362±91.6 mL), intensive care unit (ICU) monitoring time (9.04±6.35 d vs 12.48±8.34 d) and service time of breathing machine (9.47±6.24 d vs 12.98±8.25 d), and the laparoscopic operation group was superior to the open surgery group (p < 0.05). Besides, the laparoscopic operation group was also superior to the open surgery group in demand for main analgesics one week after the operation, as well as for recovery rate and incidence of complications (p < 0.05). Thus, it can be concluded that patients undergoing laparoscopic intervention are less likely to develop pulmonary infection and more likely to be cured in comparison with patients who receive open surgery. In addition, laparoscopic intervention results in less damage, lighter pain and fewer complications compared with open surgery.

Effect of sea anemone toxin anthopleurin-Q on sodium current in guinea pig ventricular myocytes

AIM

To investigate the effects of a sea anemone toxin anthopleurin-Q (AP-Q) isolated from Anthopleura xanthogrammica on sodium current (INa) in isolated guinea pig ventricular myocytes.

METHODS

Single myocytes were dissociated by enzymatic dissociation method. INa was recorded using whole-cell patch-clamp technique.

RESULTS

AP-Q (3 - 300 nmol/L) increased INa in a concentration-dependent manner. The EC50 value for increasing INa was 104 nmol/L (95 % confidence range: 78 - 130 nmol/L). AP-Q 300 nmol/L shifted the I-V curve to the leftward, changed the membrane potential of half maximal activation to more negative potential from (-36.3 +/- 2.3) mV to (-43 +/- 3) mV (n = 6, P < 0.01) and changed the membrane potential of half maximal inactivation to more positive potential from (-75 +/- 6) mV to (-59 +/- 5) mV (n = 6, P < 0.01). AP-Q 300 nmol/L shortened the half-recovery time of INa from (114 +/- 36) ms to (17 +/- 2) ms (n = 6, P < 0.01). The fast inactivation time constant (tauf) of INa was markedly increased by AP-Q 300 nmol/L.

CONCLUSION

AP-Q has a stimulating effect on I(Na) with slowing the inactivation course of INa.

[The synergistic effect of tetrandrine and rotundine on the action potential of rabbit sinus node dominant pacemaker cell and calcium currents of ventricular myocytes from guinea-pig]

Standard microelectrode technique and the whole-cell clamp technique were used to investigate the effects of tetrandrine and rotundine on the action potential of rabbit sinus node dominant pacemaker cell and calcium currents of ventricular myocytes from guinea-pig. The results indicate that: tetrandrine 1-200 mumol.L-1 and rotundine 3-300 mumol.L-1 decreased the action potential amplitude(APA), the maximal upstroke velocity (Vmax), spontaneous depolarizing velocity of phase 4(SP4) and prolonged the sinus circle length(SCL) in a dose-dependent manner. Tetrandrine 0.1 mumol.L-1 in combination with rotundine 0.3 mumol.L-1 was shown to effectively reduce the ICa of ventricular myotytes from guinea-pig, the rate of inhibition is 19.6%. The results suggest that the two drugs have a good synergistic effect on inhibiting calcium current. These results might also put forward a valuable theoretic base for using the two drugs together in treating patients.

[Effects of 4-aminopyridine on calcium currents and sodium currents in guinea pig ventricular myocytes]

AIM

To investigate the effect of 4-aminopyridine (4-AP) on ion channels of myocytes.

METHODS

L-type calcium channel and sodium channel currents were recorded in guinea pig single ventricular myocyte using whole-cell patch-clamp techniques.

RESULTS

4-AP, 0.1, 0.5 and 1.0 mmol.L-1 were shown to inhibit L-type calcium channel currents (ICa, L) and sodium channel currents (INa) concentration-dependently. The percentage of inhibition were (11.6 +/- 1.7)%, (37.5 +/- 8.3)% and (54.5 +/- 6.9)% (P < 0.01) respectively for ICa, L, and (22.1 +/- 14.3)% (P < 0.05), (39.4 +/- 8.8)% and (62.3 +/- 6.8)% (P < 0.01) respectively for INa. 4-AP 0.5 mmol.L-1 shifted the I-V curves of ICa, L and INa upwardly.

CONCLUSION

4-AP blocked L-type calcium channel and sodium channels in guinea-pig ventricular myocytes concentration-dependently.

[Effects of amiloride on calcium current in thyroxine-induced hypertrophied rat heart]

AIM

The L-Type calcium currents were investigated in normal, hypertrophied and amiloride-treated rat ventricular myocytes so as to clarify the possible cause of the action potential lengthening that has been reported in thyroxine-induced hypertrophy. The interactions between agents such as thyroxine, Ang II and phenylephrine which induced hypertrophy with amiloride on the calcium current were analyzed.

METHODS

Myocardial hypertrophy was induced by i.p. L-thyroxine in rats. The cell length, cell width and cell area were measured by image analysis technique. For recording ICaL, the whole cell patch clamp technique was used. Potassium currents were suppressed by replacing K+ ions with Cs+ ions in intracellular media, and sodium current was blocked by 50 mumol.L-1 tetrodotoxin.

RESULTS

The Ca2+ current was found to be larger in hypertrophied cells (783pA) than in normal cells (433pA) and in amiloride-treated cells (429pA). However, no significant difference was observed in current density (6.54, 8.33, 5.74 pA/pF) in normal, hypertrophied and amiloride-treated cells. ICa displayed the same voltage dependence in three cell types. The potential giving 50% of activation (V1/2) moved towards more negative and the slope of activation curve was smaller in hypertrophied cells than in normal cells and amiloride cells. When expressed as percentages, the maximal increases in ICa were obtained with 1 mumol.L-1 Ang II and 100 mumol.L-1 phenylephrine in normal cells (+45.5% and +81.8%). Thyroxine 100 mumol.L-1 showed no effect on ICa. After giving amiloride, Ang II and phenylephrine did not increase the amplitude of ICa.

CONCLUSION

At the dose of 0.5 mg.kg-1.d-1, amiloride (p.o.) was shown to prevent the amplitude of ICa from increasing and to be effective against increases of amplitude of ICa by Ang II and phenylephrine.

Effects of 7-bromoethoxybenzene-tetrahydropalmatine on voltage-dependent currents in guinea pig ventricular myocytes

AIM

To study the anti-arrhythmic mechanism of 7-bromoethoxybenzene-tetrahydropalmatine (EBP).

METHODS

Whole-cell current and voltage clamp on isolated guinea pig ventricular cells.

RESULTS

EBP 30 mumol.L-1 prolonged APD90 from 430 +/- 47 ms to 514 +/- 61 ms (n = 5, P < 0.05) without effects on the action potential amplitude and resting potential. Delayed outward K+ current and its tail current were blocked by EBP in a concentration-dependent fashion, while EBP did not change the amplitudes of the sodium current, the L type calcium current, and the inwardly rectifying potassium current.

CONCLUSION

The mechanism of anti-arrhythmic action of EBP was to prolong the APD through inhibiting the delayed rectified potassium current.

[Blocking effects of benzyltetrahydropalmatine on delayed rectified K+ currents expressed in Xenopus oocytes and in toad oocytes]

The effects of benzyltetrahydropalmatine (BTHP) on delayed rectified K+ currents (Ik) expressed in Xenopus oocytes and Ik of toad (Bufo bufo gargarizans) oocytes were studied. The Ik expressed in Xenopus oocytes was measured after microinjection of mRNA isolated from carp fish (C anratus L.) brains with double -microelectrode voltage clamp technique. The maximum and mean value of Ik expressed in Xenopus oocytes were 600 nA and 360 +/- 104 nA, respectively. BTHP reduced the current amplitude of Ik expressed in Xenopus oocytes in 10-1000 mumol.L-1 dose-dependently, EC50 was 29 mumol.L-1. Also, the reduction of Ik of toad oocytes was 9.1%, 29.1%, 54.7% and 68.6% by BTHP 10, 30, 100 and 1000 mumol.L-1, respectively, EC50 was 33 mumol.L-1. The results showed that BTHP possesses an inhibitory effect on Ik, the main ion mechanism of antiarrhythmic action of BTHP.

Comparison of effects of tetrandrine on ionic channels of isolated rat neurohypophysial terminals and Y1 mouse adrenocortical tumor cells

The effects of tetrandrine on the voltage-gated Ca2+, K+, and Na+ channels of the isolated rat neurohypophysial nerve terminals and Y1 mouse adrenocortical tumor cells were studied using standard and perforated patch-clamp techniques. Among the inward ionic currents, the T-type Ca2+ channel current (I(Ca)) in the Y1 cell line was strongly inhibited (by 52.9%) by a low concentration (13 mumol.L-1) of externally applied tetrandrine. The L-type I(Ca) in the isolated nerve terminals was also strongly inhibited (by 54.2%) by externally applied tetrandrine 33 mumol.L-1, whereas the N-type I(Ca) and Na+ current were not significantly affected by the same dose of the alkaloid. While it had no effect on the fast, transient K+ channels, external application of tetrandrine 1 mumol.L-1 blocked a slowly-gating, maxi Ca(2+)-activated K+ (K+(Ca)) channel in the nerve terminals, decreasing its P(o) by 84.4%.

CONCLUSIONS

(1) The order of the sensitivities of ionic channels to tetrandrine is K+(Ca) > T- > L- > N-type Ca2+ > Na+; (2) tetrandrine serves as a specific blocker of the slowly-gating K+(Ca) channel.

[Effects of benzyltetrahydropalmatine on rat portal vein and guinea pig myocardium]

In isolated rat portal vein, benzyltetrahydrophalmatine (BTHP) 0.3-100 mumol.L-1 dose-dependently increased the spontaneous mechanical activity. However, BTHP 300 mumol.L-1 showed an inhibitory effect on the spontaneous contraction. BTHP 200 mumol.L-1 reversed positive staircase phenomenon to negative ones in left atrium of guinea pig and inhibited the amplitude and Vmax and shortened the action potential duration (APD50) of the slow action potentials induced by high K+ (24 mmol.L-1) in guinea pig papillary muscles. BTHP reduced also the contractile force in papillary muscles of guinea pig. These results suggest that BTHP possesses calcium antagonistic effect in high concentration.

Effects of benzyltetrahydropalmatine on delayed after depolarization and triggered activity and on His-bundle electrogram and ECG in animal experiment

Standard microelectrode techniques were used to study the effects of benzyltetrahydropalmatine (BTHP) on ouabain-induced delayed after depolarization (DAD) and triggered activity in isolated guinea papillary muscles. The results indicate that ouabain-induced DAD and triggered activity were abolished by BTHP 100 mumol/L. In anesthetized rabbit ECG heart rate was reduced in a dose-dependent manner from control value of 288 +/- 14 to 261 +/- 14 (BTHP 5 mg/kg) and 226 +/- 36 bpm (BTHP 10 mg/kg). P-R interval was prolonged. In His-bundle electrogram, H-V interval and V duration were not affected, but A-H interval was prolonged from 41 +/- 3 to 45 +/- 5 ms.

[Effects of benzyltetrahydropalmatine on action potentials of myocardium and transmembrane K+ and Ca2+ currents in Purkinje fibers]

Standard microelectrode and two-microelectrode voltage clamp techniques were used to study the effects of benzyltetrahydropalmatine (BTHP) on action potentials of isolated myocardium and transmembrane K+ and Ca2+ currents in Purkinje fibers. The effect of BTHP 3-100 mumol/L consisted of prolongation of the action potential duration and reduction of delayed rectifier current (Ik) in concentration-dependent manner. At concentration above 200 mumol/L, the contractile force of the isolated myocardium was depressed and in voltage clamp experiments the slow inward current (Isi) was reduced. These results suggest that the inhibition of Ik induced by BTHP was in relation to its anti-arrhythmic action.

A new kalium channel blocker of Chinese medicinal origin--benzyltetrahydropalmatine hydrochloride

Benzyltetrahydropalmatine hydrochloride (BTHP) exhibited antiarrhythmic action in animal models. I. Electrophysiological effects of BTHP were investigated in various heart preparations. 1) BTHP markedly prolonged functional refractory period and inhibited adrenaline-induced automaticity. It decreased spontaneously beating rate of right atrium and abolished ouabain-induced delayed afterdepolarization and triggered activity of papillary muscle. 2) In standard microelectrode and contractility experiments BTHP concentration-dependently prolonged the action potential duration (APD) and effective refractory period (FRP) between 1-100 mumol/L; the force of contraction remained unchanged. 3) In voltage clamp experiments BTHP 1-100 mumol/L inhibited in dose-dependent manner the Ik with IC50 of 13 mumol/L and inhibited also Is at high concentration. 4) In monophasic action potential (MAP) of feline ventricle MAPD50 and MAPD90 were prolonged by BTHP in normal myocardium, and shortened APD induced by ischemia and reperfusion was restored to normal level. 5) In ECG and His-bundle electrogram heart rate was reduced; P-R and A-H interval were prolonged, but H-V interval and V duration were unaffected. II. BTHP showed a competitive alpha 1-adrenoceptor-blocking effect with pA2 value of 5.8 and 5.86 in rat anococcygeus muscle and rabbit aortic strips respectively. Radioligand binding assays showed that BTHP had affinity for both alpha 1 and alpha 2-adrenoceptor. The results from these experiments show that BTHP is a new K+ channel blocker of Chinese medicinal origin with alpha 1-adrenoceptor-blocking action.

Blocking action of berberine on various receptors in rat anococcygeus muscle

The contractile responses of rat anococcygeus muscle to phenylephrine, acetylcholine and 5-hydroxytryptamine in relation to berberine and to their specific antagonists were studied separately. The effects of phenylephrine and acetylcholine were blocked by berberine as well as by atropine. But the alpha-blocking action of atropine was exhibited only at high concentration. The anococcygeus muscle response to phenylephrine was competitively inhibited by berberine with a PA2 value of 6.4. The contraction induced by acetylcholine was competitively inhibited by atropine (PA2 = 8.7), whereas berberine, which differs basically from atropine, shifted the dose-response curve for acetylcholine non-parallelly to the right with its maximal response reduced concomitantly. Its pD2(1) value was 4.6. This suggests that the antagonistic action of berberine may be exerted non-specifically through a site beyond the M-cholinergic receptor. Berberine also relaxed the contraction of anococcygeus muscle induced by 5-hydroxytryptamine. The contractile responses to histamine and isoprenaline were seen only at high concentration. In addition, the response to isoprenaline was little affected by propranolol in our experiment.

Studies on the calcium antagonistic action of tetrandrine: X VI. Hemodynamic effects of tetrandrine on conscious rats

Hemodynamic study of tetrandrine (Tet) in conscious rats showed that 15 mg/kg i.v. lowered BP, LVSP, +/- dp/dtmax, and (dP/dt)P-1. The degree of diminutions was nearly equal to that of BP during the initial period, while the LVEDP was elevated. But all these parameters (except -dp/dtmax) recovered gradually and earlier than BP, and LVEDP decreased to a level slightly lower than that of control. These results indicate that the hypotensive action of Tet is mainly due to its inhibition of cardiac contractility at the early period, but due to vasodilatation in the later stage. The HR was slowed down abruptly followed by a reflex acceleration, and than a gradual but sustained decrease in HR supervened with i.v. Tet. When large dose (40 mg/kg) of Tet i.v. caused a cardiac standstill with the R wave of ECG persisting for a few minutes, it means that an excitation-contraction decoupling occurred as that found on isolated myocardial preparation treated with verapamil and Tet.