[Early diagnosis and early treatment for liver cancer in Qidong: survival of patients and effectiveness of screening].

Objective: To evaluate the patients' survival and effectiveness of the live cancer screening for population at high risk for liver cancer in Qidong. Methods: According to the Expert Scheme proposed the Expert Committee of Early Detection and Early Treatment, China Cancer Foundation, diagnostical screening by using combined methods of alpha-fetoprotein and B ultrasound monitoring were carried out biannually in individuals with positive HBsAg who were screened from Qidong area. The evaluation indices of the effectiveness are task completion rate of screening, detection rate of liver cancer, early diagnosis rate, and treatment rate. The deadline of the follow-up for the surviving outcome was March 31, 2016. The life-table method was used to calculate the observed survival, and to make comparison and significant tests between survival rates in Group A (those found via repeated periodic screening) and Group B (those diagnosed without periodic screening). Results: Since 2007, 38 016 target population have been screened, and 3 703(9.74%) individuals with positive HBsAg were found. Except for 29 patients with liver cancer at the initial screening, 3 674 persons in the cohort were followed up; 268 patients with liver cancer were detected from the 33 199 person-times screening, with an annual detection rate of 1.61%. Of them, 186 patients were found in Group A(1.12%), in which 149 patients were the early cases, with an early detection rate of 80.11%; 167 out of 186(89.78%) patients received treatment after diagnosis. The incidence of liver cancer in this HBsAg (+ ) cohort of 25 452 person-years was 1 052.96 per 100 000 annually, 187 cases in males(1 488.45/100 000)and 81 cases in females(628.46/100 000). The 1-, 3-, 5-, and 8-year survival of all patients with liver cancer were 64.55%, 40.50%, 32.54%, and 19.65%, respectively. The 1-, 3-, 5-, and 8-year survival rates were 77.16%, 49.04%, 38.53%, and 24.25% in Group A, and were 36.25%, 21.21%, 21.21%, and 0% in Group B, respectively, with significant differences between two groups (P<0.05). Conclusion: The findings show that screening of individuals at high-risk of development of liver cancer, with semiannual AFP and B ultrasound, according to the Expert Scheme, is effective not only in increasing detection rate but also in detecting liver cancer at early stage, and in improving patients' survival as well.

[Rheumatoid arthritis involving tibialis posterior tendon: study on the early diagnostic value of power Doppler ultrasonography and comparison with surgery].

Objective: To explore the value of power Doppler ultrasonography (PDUS) in the early diagnosis of tibialis posterior tendon injury induced by rheumatoid arthritis (RA). Method: From January 2014 to December 2015, a total of 48 cases (60 feet) of RA tendinopathy group were selected as the research subjects from Guanghua Hospital; 12 cases(20 feet) of non-RA tendinopathy group and 10 cases (20 feet) of healthy volunteers were selected as control group.The blood flow signals of pannus were observed by PDUS to determine whether the tendon was injured or the degree of the injury. The following indexes were compared and analyzed by Chi-square testing: (1)positive rate of blood flow signal; (2)grade of blood flow signal; (3)spatial distribution of blood flow signal: diffusibility or local. Results: Of 70 cases(100 feet) in the study, the positive blood flow signals were only in the RA(88.3%) and non-RA group(40.0%) .Grade Ⅲ in RA was 20.0%, while this was not observed in non-RA . Grade Ⅱ in RA and non-RA was 36.7% and 10.0% , respectively. There were significant differences in the positive rate and grades between RA and non-RA group (P<0.01). The spatial distribution of blood flow signal in RA was significantly different from that in non-RA. In RA, they can be detected in the whole tendon.However, they were mainly distributed around the scaphoid in non-RA. In this study, three patients with grade Ⅲwere treated with surgery. The intraoperative findings were consistent with the preoperative ultrasound results. Conclusions: PDUS can be used to detect the neovascular formation of tendon synovitis. It can detect the early tendon injury before the appearance of foot deformity induced by RA, which can guide clinical early intervention treatment and prevent the occurrence of deformity and other serious consequences.

[Influence of leptin receptor gene K109R polymorphism on the risk of nonalcoholic fatty liver disease and its interaction with PNPLA3 I148M polymorphism].

OBJECTIVE: To investigate the influence of leptin receptor (LEPR) gene K109R polymorphism on the risk of nonalcoholic fatty liver disease (NAFLD) and its interaction with PNPLA3 I148M polymorphism in the Han Chinese population in Qingdao, China. METHODS: Blood samples were collected from 296 NAFLD patients and 321 healthy controls, and the genotypes of these patients were determined by PCR and genotyping. Related statistical analyses were performed to compare genotypes, alleles, and clinical data between the two groups. Generalized multifactor dimensionality reduction (GMDR) was used to investigate the interaction between LEPR K109R and PNPLA3 I148M genes. RESULTS: The distribution of LEPR K109R genotypes and alleles showed no significant differences between the NAFLD group and the control group (P > 0.05). PNPLA3 I148M gene polymorphisms were closely associated with the risk of NAFLD, and the risk of NAFLD in G mutant gene carriers was 2.07 times that in patients who did not carry this gene (OR = 2.07, 95% CI 1.423-3.013, P < 0.001). The joint action of LEPR K109R and PNPLA3 I148M significantly increased the risk of NAFL (OR = 3.393, 95% CI 1.856-6.201, P < 0.001). CONCLUSION: In the Han Chinese population in Qingdao, LEPR K109R gene polymorphism is not associated with the risk of NAFLD, but its interaction with PNPLA3 I148M polymorphism can significantly increase the risk of NAFLD.

Orbital angular momentum entanglement via fork-poling nonlinear photonic crystals.

We report a compact scheme for the generation and manipulation of photon pairs entangled in the orbital angular momentum (OAM) from the fork-poling quadratic nonlinear crystal. The χ(2)-modulation in this crystal is designed for fulfilling a tilted quasi-phase-matching geometry to ensure the efficient generation of entangled photons as well as for transferring of topological charge of the crystal to the photon pairs. Numerical results show that the OAM of photon pair is anti-correlated and the degree of OAM entanglement can be enhanced by modulating the topological charge of crystal, which indicates a feasible extension to high-dimensional OAM entanglement. These studies suggest that the fork-poling nonlinear photonic crystal a unique platform for compact generation and manipulation of high-dimensional and high-order OAM entanglement, which may have potential applications in quantum communication, quantum cryptography and quantum remote sensing.

Silibinin attenuates amyloid beta(25-35) peptide-induced memory impairments: implication of inducible nitric-oxide synthase and tumor necrosis factor-alpha in mice.

In Alzheimer's disease (AD), the deposition of amyloid peptides is invariably associated with oxidative stress and inflammatory responses. Silibinin (silybin), a flavonoid derived from the herb milk thistle, has potent anti-inflammatory and antioxidant activities. However, it remains unclear whether silibinin improves amyloid beta (Abeta) peptide-induced neurotoxicity. In this study, we examined the effect of silibinin on the fear-conditioning memory deficits, inflammatory response, and oxidative stress induced by the intracerebroventricular injection of Abeta peptide(25-35) (Abeta(25-35)) in mice. Mice were treated with silibinin (2, 20, and 200 mg/kg p.o., once a day for 8 days) from the day of the Abeta(25-35) injection (day 0). Memory function was evaluated in cued and contextual fear-conditioning tests (day 6). Nitrotyrosine levels in the hippocampus and amygdala were examined (day 8). The mRNA expression of inducible nitric-oxide synthase (iNOS) and tumor necrosis factor-alpha (TNF-alpha) in the hippocampus and amygdala was measured 2 h after the Abeta(25-35) injection. We found that silibinin significantly attenuated memory deficits caused by Abeta(25-35) in the cued and contextual fear-conditioning test. Silibinin significantly inhibited the increase in nitrotyrosine levels in the hippocampus and amygdala induced by Abeta(25-35). Nitrotyrosine levels in these regions were negatively correlated with memory performance. Moreover, real-time RT-PCR revealed that silibinin inhibited the overexpression of iNOS and TNF-alpha mRNA in the hippocampus and amygdala induced by Abeta(25-35). These findings suggest that silibinin (i) attenuates memory impairment through amelioration of oxidative stress and inflammatory response induced by Abeta(25-35) and (ii) may be a potential candidate for an AD medication.

[Active etiological surveillance for foodborne diseases in Guangdong province, 2013-2014].

Objective: To study the infection status, serotypes, drug resistance and molecular characteristics of Salmonella, Shigella, Vibrio parahemolyticus, enterotoxigenic Escherichia (E.) coli (ETEC), pathogenic E. coli (EPEC), Shiga Toxin producing E. coli (STEC) and Enteroinvasive E. coli (EIEC) collected from diarrhea patients in Guangdong. Methods: The strains of Salmonella, Shigella, V. parahemolyticus and 4 kinds of E. coli isolated from foodborne diseases surveillance during 2013-2014 were collected to conduct serotyping, drug resistance test and pulsed-field gel electrophoresis (PFGE). Results: A total of 3 372 stains of pathogens were isolated from 57 834 stool samples during 2013-2014, the overall positive rate was 5.83% and the positive rate of Salmonella was highest, followed by that of V. parahemolyticus, 4 kinds of E. coli and Shigella. And 3 213 strains of Salmonella were divided into 143 serotypes. The most prevalent serotypes were Salmonella typhimurium, 4, 5, 12: i:-, Enteritidis, Stanley and Derby. Salmonella was sensitive to cephalosporin and fluoroquinolones, and showed significant differences in drug resistance rate among different serotypes. In top 10 common serotypes, S. enteritidis and S. derby were most resistant to cephalosporin and ciprofloxacin respectively. PFGE was performed for 2 289 strains of Salmonella, showing distribution diversity and significant fingerprint polymorphisms. The 85 strains of V. parahemolyticus were divided into 10 serotypes, O3∶K6 (61.18%) was the most common serotype, followed by O4∶K8. The results showed that the carrying rate of virulence genes tdh (81.18%) was high, while the carrying rate of trh was low (7.06%), and there were 10 strains carrying no the two kinds of virulence genes. The sensitive rate of V. parahemolyticus to imipenem, nalidixic acid, SMZ-TMP, chloramphenicol and tetracycline were more than 95%. Thirteen strains of Shigella were detected, including 9 strains of Shigella sonnei, 3 strains of Shigella flexneri and 1 strains of Shigella bogdii. The strains all showed sensitivity to ceftazidime, ciprofloxacin and chloramphenicol (76.92%). There were 86 strains of E. coli detected, including 29 strains of ETEC (33.72%), 27 strains of EPEC (31.39%), 27 strains of STEC (31.39%) and 3 strains of EIEC (3.48%). Conclusions: In the active etiological surveillance for foodborne diseases in Guangdong during 2013-2014, the detection rate of Salmonella was highest (5.57% ), followed by that of V. parahemolyticus, 4 kinds of E. coli and Shigella. Salmonella, V. parahemolyticus and Shigella were sensitive to cephalosporin and fluoroquinolones. Clustered cases of Salmonella infection were found in the surveillance, but no outbreaks occurred.

Mutations in SID2, a novel gene in Saccharomyces cerevisiae, cause synthetic lethality with sic1 deletion and may cause a defect during S phase.

SIC1 encodes a nonessential B-type cyclin/CDK inhibitor that functions at the G1/S transition and the exit from mitosis. To understand more completely the regulation of these transitions, mutations causing synthetic lethality with sic1 Delta were isolated. In this screen, we identified a novel gene, SID2, which encodes an essential protein that appears to be required for DNA replication or repair. sid2-1 sic1 Delta strains and sid2-21 temperature-sensitive strains arrest preanaphase as large-budded cells with a single nucleus, a short spindle, and an approximately 2C DNA content. RAD9, which is necessary for the DNA damage checkpoint, is required for the preanaphase arrest of sid2-1 sic1 Delta cells. Analysis of chromosomes in mutant sid2-21 cells by field inversion gel electrophoresis suggests the presence of replication forks and bubbles at the arrest. Deleting the two S phase cyclins, CLB5 and CLB6, substantially suppresses the sid2-1 sic1 Delta inviability, while stabilizing Clb5 protein exacerbates the defects of sid2-1 sic1 Delta cells. In synchronized sid2-1 mutant strains, the onset of replication appears normal, but completion of DNA synthesis is delayed. sid2-1 mutants are sensitive to hydroxyurea indicating that sid2-1 cells may suffer DNA damage that, when combined with additional insult, leads to a decrease in viability. Consistent with this hypothesis, sid2-1 rad9 cells are dead or very slow growing even when SIC1 is expressed.

Modulation of sodium current by lactate in guinea pig ventricular myocytes.

OBJECTIVE: The aim was to elucidate whether or not lactate modifies the fast sodium current (INa) in cardiac cells. METHODS: A tight seal whole cell clamp technique was used to record the action potentials and INa in single ventricular cells from the guinea pig heart. RESULTS: In voltage clamp experiments, superfusion with 20 mM lactate shifted both the normalised conductance (gNa)-voltage relationship and the channel availability curve toward hyperpolarisation by approximately 4 mV, but did not affect the maximum conductance (gNa,max). In the test solution containing only CaCl2 as the main divalent component, 20 mM lactate reduced the ionised calcium concentration from 1.02 to 0.84 mM. When the calcium concentration was kept constant by the addition of CaCl2 into the lactate containing solution the lactate effect was nullified. However, a change in the calcium concentration from 1.0 to 0.84 mM without lactate induced a 4 mV negative shift of the channel availability curve. Current clamp experiments in Tyrode solution showed that 20 mM lactate shifted the threshold for the action potential upstroke by 2.5-3 mV, in accordance with the voltage clamp experiments. CONCLUSIONS: Lactate modifies INa of ventricular myocytes by shifting its kinetics toward hyperpolarisation. This shift seems to be caused exclusively by a decrease in the ionised divalent cation concentrations and a resultant change in the negative surface charge of the sarcolemma.

Does dopamine act on myocardial cells?

We examined the electrophysiological effects of dopamine on the single myocardial cells isolated from the rat and rabbit heart. Dopamine at a concentration of 1 or 10 microM did not affect the L-type Ca2+ current (ICa) or the transient outward current (ITO) in rat ventricular, rabbit atrial, ventricular, and sinoatrial node cells. It did not induce any detectable change in the action potential configuration of the rabbit ventricular cells either. We conclude that dopamine does not directly act on myocardial cells at least in terms of the electrophysiological properties.

Ethanol inhibition of Ca2+ and Na+ currents in the guinea-pig heart.

The effects of ethanol on L-type Ca2+ and fast Na+ currents (ICa and INa, respectively) were examined using the whole-cell patch-clamp experiments on guinea-pig ventricular cells. At a clinically relevant concentration of 24 mM, ethanol slightly but significantly shortened the action potential duration, and reduced the ICa by 7 +/- 4% (mean +/- S.D.). This concentration of ethanol did not affect INa, but a lethal concentration of ethanol (80 mM) significantly inhibited INa by 13 +/- 5%. The voltage dependence of INa activation was not affected by ethanol, whereas the inhibitions of ICa by 80 mM ethanol and INa by 240 mM were both accompanied by a several mV shift in the channel availability curve toward more negative potentials, suggesting that the channels in the inactivated state are more susceptible to ethanol. The ICa inhibition by ethanol at clinically relevant concentrations could contribute to a negative inotropic effect, action potential shortening and development of arrhythmias, while the pathophysiological significance of ethanol inhibition of INa seems less important.

[The synergistic action of guanghuoxiang volatile oil and sodium artesunate against Plasmodium berghei and reversal of SA-resistant Plasmodium berghei].

OBJECTIVE: To study the synergistic action of a combination of guanghuoxiang volatile oil (B) and sodium artesunate (SA) against Plasmodium berghei (P. b) and the resistance-reversal activity against SA-resistant P. b (P. b SA-R). METHODS: Mice infected with P. b N or P. b R were treated with a combination of B and SA respectively by 4-day suppressive test method and linear regression to calculate the SD50 of B and SA for each drug alone and in combination (equally effective dose compatibility). RESULTS: B alone, N:SD50 = 87.64 +/- 19.58(GKD), R:SD50 = 43.24 +/- 7.71(GKD); SA alone, N:SD50 = 0.88 +/- 0.01(MGKD), R:SD50 = 27.69 +/- 0.93(MGKD). B and SA combination, N:B SD50 = 36.89 +/- 4.57(GKD), SA SD50 = 0.39 +/- 0.05 (MGKD); R:B SD50 = 7.40 +/- 1.30(GKD), SA SD50 = 4.21 +/- 0.74(MGKD). The synergistic indexes of B and SA in combination were 2.2 for N and 6.6 for R, respectivly. The multiple of resistance reversal of B vs SA was 6.6. The relative reversal rate was 87.6%. CONCLUSION: A combination of B and SA may enhance the antimalarial effect against P. b and reverse the SA-resistance of P. b and delay the occurrence of resistance to SA in N.

[Star figure in medical monitoring during lower body negative pressure test].

Objective. To find a real-time, quick and audio-visual method to evaluate the subject's physiological function condition and possible development. Method. Star figure technique was adopted to analyse multiple physiological indices during lower body negative pressure test (LBNP). Based on the character and stability of the stars figure, the steadiness of the subjects physiological function can be judged. Result. Physiological function can be accurately assessed only when the model of stress response of an individual is formed. Conclusion. The changes of star figure can indicate the possible development of the physiological function stage.

[Hemodynamic changes of pulmonary circulation during HDT -30 degrees].

OBJECTIVE: To study the hemodynamic changes of pulmonary circulation during simulated weightlessness. METHOD: 12 subjects were studied using echocardiography and electrocardiography during head-down tilt (HDT) of -30 degrees lasting for 45 min. RESULT: Right ventricular ejection time increased significantly (P<0.05); peak velocity of pulmonary arterial blood flow decreased significantly (P<0.05); acceleration time of pulmonary arterial blood flow did not change significantly; significant decrease of right ventricular output occurred at the 10th minute and the 30th minute (P<0.05); pre-ejection period significantly decreased at the 30th minute and recovery. Heart rate, mean velocity of pulmonary arterial blood flow, and acceleration of pulmonary arterial blood flow did not change significantly; left ventricular cardiac output, stroke volume and blood pressure remained constant throughout the experiment. CONCLUSION: Changes of the parameters of pulmonary circulation suggested that pulmonary resistance increased, and the increase of pulmonary resistance maybe be the direct cause of the increase of pulmonary arterial pressure.

[Effects of -30 degrees head down tilt on lung function].

OBJECTIVE: To investigate the effects of short-term simulated weightlessness on lung function in healthy males. METHOD: -30 degrees head down tilt for 45 min was used to simulate short-period weightlessness. Lung function of 12 healthy males, aged 18-21, were studied with plethysmography during seating, supine and head down tilt positions. At the same time, blood flow in pulmonary artery and function of right ventricle were measured with Doppler Echo-Cardiography. Comparative analysis was done. RESULT: As body position changed from seating or supine into head down tilt, FVC, FEV1, FEV1%, MVV, VA and IVC decreased. The change of MVV was the most prominent (P < 0.000). As the position changed, pulmonary diffusion increased dramatically (DL(CO) P<0.001, K(CO) P<0.000). CONCLUSION: HDT may lead to a decrease of pulmonary ventilation and lung capacity. The increased pulmonary diffusion might be related to uniform distribution of pulmonary blood flow and increased effective pulmonary vascular bed.

[Analysis of heart rate variability during acute exposure to hypoxia].

Objective. To investigate the changes of autonomic nervous system during acute exposure to an altitude of 5000 m by analysing heart rate variability (HRV). Method. 11 healthy male volunteers aged 18-30 were observed during inhalation of low oxygen gas mixture to simulate acute exposure to hypoxia. HRV was analyzed with both time domain and frequency domain methods. The eleven subjects were divided into two groups--Group A with good tolerance and Group B with poor tolerance. Result. During hypoxia heart rate increased markedly and RMSSD (the square root of the mean squared differences of successive RR intervals) decreased markedly; normalized low-frequency (LFn. u.) and LF/HF ratio increased significantly, while HF and normalized high-frequency (HFn. u.) reduced significantly. LFn. u. and LF/HF increased more apparently in group B than in group A during hypoxia of 5-10 min and RMSSD decreased more in group B during 10-15 min. Conclusion. The results suggested that cardiac sympathetic activity increased and cardiac vagal activity decreased during acute hypoxia. The analysis of HRV could predict the tolerance to hypoxia.

Silibinin prevents amyloid beta peptide-induced memory impairment and oxidative stress in mice.

BACKGROUND AND PURPOSE: Accumulated evidence suggests that oxidative stress is involved in amyloid beta (Abeta)-induced cognitive dysfunction. Silibinin (silybin), a flavonoid derived from the herb milk thistle (Silybum marianum), has been shown to have antioxidative properties; however, it remains unclear whether silibinin improves Abeta-induced neurotoxicity. In the present study, we examined the effect of silibinin on the memory impairment and accumulation of oxidative stress induced by Abeta(25-35) in mice. EXPERIMENTAL APPROACH: Aggregated Abeta(25-35) (3 nmol) was intracerebroventricularly administered to mice. Treatment with silibinin (2, 20 and 200 mg.kg(-1), once a day, p.o.) was started immediately after the injection of Abeta(25-35). Locomotor activity was evaluated 6 days after the Abeta(25-35) treatment, and cognitive function was evaluated in a Y-maze and novel object recognition tests 6-11 days after the Abeta(25-35) treatment. The levels of lipid peroxidation (malondialdehyde) and antioxidant (glutathione) in the hippocampus were measured 7 days after the Abeta(25-35) injection. KEY RESULTS: Silibinin prevented the memory impairment induced by Abeta(25-35) in the Y-maze and novel object recognition tests. Repeated treatment with silibinin attenuated the Abeta(25-35)-induced accumulation of malondialdehyde and depletion of glutathione in the hippocampus. CONCLUSIONS AND IMPLICATIONS: Silibinin prevents memory impairment and oxidative damage induced by Abeta(25-35) and may be a potential therapeutic agent for Alzheimer's disease.

Effects of changrolin on potassium currents in guinea pig and rabbit single heart cells.

AIM: To elucidate whether or not changrolin (CRL) modifies the potassium currents (ITO, IK, and IKl) in myocardial cells. METHODS: A tight seal whole-cell patch-clamp technique was used to record ITO, IK, and IKl in single cells isolated from guinea pig and rabbit hearts. RESULTS: At a clinically relevant concentration, CRL 50 mumol.L-1 inhibited the transient outward current (ITO) by 17.7% +/- 2.4% (n = 8) in rabbit atrial cells. The voltage-dependence of steady-state inactivation of ITO was not affected by CRL. This concentration of CRL did not influence the time-independent inward rectifier or the delayed rectifier K+ currents (IKl and IK, respectively) in rabbit and guinea pig ventricular cells. CONCLUSION: CRL inhibited ITO, but not IK nor IKl.

Electrophysiological effects of changrolin, an anti-arrhythmic agent derived from Dichroa febrifuga, on guinea-pig and rabbit heart cells.

1. The electrophysiological effects of changrolin (CRL), a Chinese anti-arrhythmic drug derived from a traditional antimalarial plant, were examined using the whole-cell patch-clamp method on single cells isolated from guinea-pig and rabbit hearts. 2. At a clinically relevant concentration of 50 mumol/L changrolin inhibited ICa by 19.3 +/- 6.0% and 17.3 +/- 2.6% in guinea-pig and rabbit ventricular cells, respectively. The voltage-dependent channel availability curve was not affected. The CRL effect was enhanced to a small extent during a repetitive stimulation at 2 Hz. 3. INa was resistant to CRL and the channel availability curve was also unaffected. A small use-dependent inhibition was observed only when the INa was elicited at 5 Hz in the presence of 300 mumol/L CRL. 4. At 50 mumol/L, CRL did not affect the time-independent inward rectifier and the delayed rectifier K+ currents (IK1 and IK, respectively), but inhibited the transient outward current (ITO) by 17.7 +/- 2.4%. Changrolin significantly shortened the action potential duration in both guinea-pig and rabbit ventricular cells. 5. In conclusion, CRL inhibits ICa and ITO but has little effect on INa.

Angiotensin II inhibition of L-type Ca2+ current in sinoatrial node cells of rabbits.

The actions of angiotensin II (ANG II) were examined in the spontaneously active cells isolated from the rabbit sinoatrial node, using the nystatin-permeabilized, whole cell, patch-clamp method. At 30 nM, ANG II significantly lowered the spontaneous firing rate of the action potentials from 212 +/- 21 to 172 +/- 32 beats/min, with a concomitant reduction in the action potential amplitude. The voltage-clamp experiments showed that ANG II inhibited the L-type Ca2+ current (ICa) with a dissociation constant (Kd) of approximately 4 nM and a maximal inhibition of 30%. The inhibition was blocked by an AT1-receptor antagonist CV11974. Acetylcholine (ACh) at 10 microM reduced the ICa by 42 +/- 12%, and ANG II did not cause any further inhibition in the presence of ACh. At 100 nM, ANG II reduced the ICa by only 12% in the presence of 2 microM isoproterenol, and a similar inhibition was observed with 0.1 microM ACh. ANG II did not affect the dibutyryl adenosine 3',5'-cyclic monophosphate-stimulated ICa. Protein kinase C activator 12-O-tetra-decanoylphorbol-13-acetate did not mimic ANG II in the effects on ICa, and preincubation of the cells with calphostin C, a protein kinase C inhibitor, did not attenuate the ANG II effect. ANG II exerts a negative chronotropic effect in the pacemaker cells as its direct action through a pathway involving adenosine 3',5'-cyclic monophosphate-dependent protein kinase.