Poor prescribing is continual.
Explore the source record for details and available documents.
Drug Prescriptions↗
Biomedical subjects
Albert Ferro
Publications and source records attributed to Albert Ferro.
Mechanisms underlying beta2-adrenoceptor-mediated nitric oxide generation by human umbilical vein endothelial cells.
Endothelial beta(2)-adrenoceptor (beta(2)AR) stimulation increases nitric oxide (NO) generation, but the underlying cellular mechanisms are unclear. We examined the role of l-arginine transport and of phosphorylation of NO synthase 3 (NOS-3) in beta(2)AR-mediated NO biosynthesis by human umbilical vein endothelial cells (HUVEC). To this end, we assessed l-arginine uptake, NOS activity (from l-arginine to l-citrulline conversion), membrane potential (using [(3)H]tetraphenylphosphonium), as well as serine phosphorylation of NOS-3 (by Western blotting and mass spectrometry), in HUVEC treated with betaAR agonists or cyclic AMP-elevating agents. beta(2)AR stimulation increased l-arginine transport, as did cyclic AMP elevation with either forskolin or dibutyryl cyclic AMP, and this increase was inhibitable by N-ethylmaleimide. Blockade of l-arginine uptake by l-lysine inhibited NOS activity and, conversely, blockade of NOS using N(omega)-nitro-l-arginine methyl ester (l-NAME) inhibited l-arginine transport. beta(2)AR stimulation also caused a membrane hyperpolarization inhibitable by l-NAME, suggesting that the increase in l-arginine uptake occurred in response to NO-mediated hyperpolarization. beta(2)AR activation also increased NOS activity and phosphorylation of NOS-3 on serine-1177, and these increases were attenuated by inhibition of protein kinase A (PKA), phosphatidylinositol 3-kinase (PI3K) or Akt, and abolished by coinhibition of PKA and Akt. These findings suggest that beta(2)AR-mediated NOS-3 activation in HUVEC is mediated through phosphorylation of NOS-3 on serine-1177 through both the PKA and the PI3K/Akt systems, and is sustained by an increase in l-arginine uptake resulting from NO-mediated membrane hyperpolarization.
Amino Acid Sequence↗
beta-adrenoceptors and potassium channels.
Explore the source record for details and available documents.
Animals↗
Cardiac stem cell therapy: present and future.
The last decade has seen great strides in the drug treatment of myocardial infarction and consequent heart failure, with associated improvements in quality of life, haemodynamics and survival. Despite this, the benefits of pharmacotherapy are limited in the more severe cases, and mortality and morbidity remain high. The ability to replace damaged myocardium by the use of stem cell therapy offers a new and potentially exciting treatment modality, but its benefits are at present far from established. Here we briefly review the current state of cardiac stem cell therapy and consider its future.
Bone Marrow Transplantation↗
Pyridoxine prevents dysfunction of endothelial cell nitric oxide production in response to low-density lipoprotein.
Low-density lipoprotein (LDL) inhibits endothelium-dependent vasorelaxation. The aim of this study was to determine whether pyridoxine supplementation improves indices of LDL-induced endothelial dysfunction. Human umbilical vein endothelial cells (HUVEC) were incubated with native LDL (nLDL) from healthy subjects, oxidized LDL (oxLDL, formed by nLDL oxidation) or nLDL from type II diabetic patients (dLDL), in the absence or presence of pyridoxine; nitric oxide synthase (NOS) activity, cyclic GMP and expression of NOS isoforms were measured, as well as thiobarbituric acid reactive substances (TBARS) in HUVEC supernatants and amino acid concentrations in HUVEC lysates. All LDL species inhibited total NOS activity, whilst increasing the much smaller Ca2+-independent component of NOS activity, the effects of oxLDL being greatest and those of nLDL smallest; in accordance with these findings, NOS type 3 expression decreased and NOS type 2 expression increased, with a resultant decrease in bioactive nitric oxide (NO), in HUVEC treated with each LDL species, with the same rank order of potency. LDL species also increased TBARS in HUVEC supernatants as well as homocysteine concentrations in HUVEC lysates, nLDL < dLDL < oxLDL. Pyridoxine largely prevented all LDL-induced changes in NOS activity and isoform expression, as well as in TBARS and homocysteine. The findings suggest that pyridoxine prevents LDL-induced dysfunction of endothelial cell NO generation, most likely through its antioxidant effects as well as through its effects on cellular homocysteine metabolism. This has important potential therapeutic implications for cardiovascular disease prevention.
Cyclic GMP↗
A genetic variant c.553G > T in the apolipoprotein A5 gene is associated with an increased risk of coronary artery disease and altered triglyceride levels in a Chinese population.
Elevation in plasma triglycerides (TG) has been widely accepted as a coronary artery disease (CAD) risk predictor. Recently, a new apolipoprotein playing an important role in TG metabolism named apolipoprotein AV (apoAV) was discovered, which is encoded by the APOA5 gene. Several single nucleotide polymorphisms (SNPs) of APOA5 associated with increased TG concentrations have been identified. We here report that a recently identified genetic variant, c.553G>T in the APOA5 gene which causes a substitution of a cysteine for a glycine residue at amino acid residue 185(G185C) is also associated with increased TG levels. To investigate the association between this genetic variation and the risk of CAD, a case-control study comprising 232 patients with CAD and 302 controls from the same area of China was performed. The minor allele frequencies of c.553G > T for the CAD and control groups were 7.76 and 3.97%, respectively (P = 0.008). In both the CAD and control groups, the T allele carriers had higher serum TG levels than homozygous carriers of the major G allele (CAD group: 2.67 +/- 1.48 mmol/l versus 1.95 +/- 1.02 mmol/l, P = 0.021; controls: 2.31 +/- 1.20 mmol/l versus 1.68 +/- 0.95 mmol/l, P = 0.002). After adjustment for age, gender, body mass index, smoking status, glucose and presence of hypertension, the odds ratio (OR) for CAD in the T allele carriers was 2.089 (95% CI = 1.140-3.830, P = 0.017), in comparison to the individuals without the T allele. These results suggest that the APOA5 c.553G > T polymorphism is an important predictor for hypertriglyceridemia and CAD.
Amino Acid Substitution↗
Inhibition of human endothelial cell nitric oxide synthesis by advanced glycation end-products but not glucose: relevance to diabetes.
Endothelial dysfunction, with decreased NO (nitric oxide) biosynthesis, may play a pathophysiological role in diabetic vasculopathy. The aim of the present study was to determine the relative contributions of glucose and AGE (advanced glycation end-product) accumulation in suppressing NOS-3 (the endothelial isoform of NO synthase). Cultured HUVECs (human umbilical vein endothelial cells) were incubated with different concentrations of glucose, unmodified albumin or AGE-modified albumin for different times. NOS activity was measured from the conversion of L-[(3)H]arginine into L-[(3)H]citrulline, and the expression, serine phosphorylation and O-glycosylation of NOS-3 were determined by Western blotting. High (25 mmol/l) glucose, for up to 12 days of incubation, had no effect on the activity or expression of NOS-3, nor on its degree of serine phosphorylation or O-glycosylation, compared with physiological (5 mmol/l) glucose. By contrast, AGE-modified albumin exerted a concentration- and time-dependent suppression of NOS-3 expression in HUVECs at a range of concentrations (0-200 mg/l) found in diabetic plasma; this was evident after 24 h, whereas inhibition of NOS activity was seen after only 3 h incubation with AGE-modified albumin, consistent with our previous observations of rapid suppression of NOS-3 serine phosphorylation and NOS-3 activity by AGE-modified albumin. In conclusion, AGE-modified albumin suppresses NOS-3 activity in HUVECs through two mechanisms: one rapid, involving suppression of its serine phosphorylation, and another slower, involving a decrease in its expression. We also conclude that, in the context of the chronic hyperglycaemia in diabetes, the effects of AGEs on endothelial NO biosynthesis are considerably more important than those of glucose.
Cells, Cultured↗
Nitric oxide-dependent beta2-adrenergic dilatation of rat aorta is mediated through activation of both protein kinase A and Akt.
Vasorelaxation to beta(2)-adrenoceptor stimulation occurs through both endothelium-dependent and endothelium-independent mechanisms, and the former is mediated through Ca(2+)-independent activation of endothelial-type nitric oxide synthase (NOS-3). Since Ca(2+)-independent NOS-3 activation may occur through its serine phosphorylation via protein kinase A (PKA) or Akt, we determined the PKA and Akt dependency of beta(2)-adrenergic relaxation of rat aorta. Rat aortic rings were pre-incubated with the PKA inhibitor H-89 (10(-7) m), the phosphatidylinositol 3-kinase (PI3K) inhibitor wortmannin (5 x 10(-7) m), Akt inhibitor (10(-5) m), or vehicle, in the absence or presence of the NOS inhibitor N(G)-nitro-l-arginine methyl ester (l-NAME, 10(-4) m). Rings were then contracted with phenylephrine (10(-7) m), and concentration-relaxation responses determined to the beta(2)-adrenoceptor agonist albuterol. Rings exhibited a concentration-dependent relaxation to albuterol: pEC(50) 6.9+/-0.2, E(max) 88.2+/-4.0%. l-NAME attenuated E(max) to 60.2+/-3.5% (P<0.001). In the presence of l-NAME, wortmannin or Akt inhibitor did not influence albuterol responses, whereas H-89 reduced E(max) further, to 27.5+/-2.2% (P<0.001). In the absence of l-NAME, E(max) to albuterol was reduced by H-89, wortmannin or Akt inhibitor, to 56.2+/-2.2, 56.0+/-1.6 and 55.4+/-1.8%, respectively (P<0.001 for each); the combinations H-89 plus wortmannin or H-89 plus Akt inhibitor reduced E(max) further still. Western blotting of NOS-3 immunoprecipitates from rat aortas confirmed that albuterol increased serine phosphorylation of NOS-3, and this increase was attenuated by H-89 or Akt inhibitor. Our results indicate that beta(2)-adrenoceptor stimulation relaxes rat aorta through both NO-dependent and independent mechanisms. The latter is predominantly PKA-mediated, whereas the former occurs through both PKA and PI3K/Akt activation.
Adrenergic beta-2 Receptor Agonists↗
Inhibition of endothelial nitric oxide generation by low-density lipoprotein is partially prevented by L-arginine and L-ascorbate.
We evaluated, in endothelial cells, the relative effectiveness of L-arginine and L-ascorbate in preventing the decrease in nitric oxide (NO) production in response to native low-density lipoprotein (LDL) from healthy subjects (nLDL), oxidized LDL (oxLDL, formed by nLDL oxidation) or native LDL from type 2 diabetic patients (dLDL). Human umbilical vein endothelial cells (HUVEC) were exposed to nLDL, dLDL or oxLDL (100 mg protein/L), in the absence or presence of L-arginine 10(-4)mol/L and/or L-ascorbate 10(-4)mol/L; NO synthase (NOS) activity and cyclic guanosine-3',5'-monophosphate (cGMP) were measured by the conversion of L-[3H]-arginine to L-[3H]citrulline and by radioimmunoassay, respectively. Both L-arginine and L-ascorbate increased cGMP in HUVEC co-incubated with any LDL species, although to lower levels than found in the absence of LDL. L-ascorbate did not affect NOS activity, whereas L-arginine increased it, both in the absence and presence of all LDL species. The effects of combined L-arginine and L-ascorbate on NOS activity and cGMP were no greater than those of L-arginine alone. Our results suggest that L-arginine or L-ascorbate can ameliorate, but not normalize, NO production in this situation, and that combining L-arginine with L-ascorbate is unlikely to produce additional benefit as compared with L-arginine alone.
Adult↗
Rabbit aortic endothelial dysfunction by low-density lipoprotein is attenuated by L-arginine, L-ascorbate and pyridoxine.
1. We investigated the relative effectiveness of L-arginine, L-ascorbate and pyridoxine in preventing the impairment of endothelium-mediated vasorelaxation induced by native low-density lipoprotein (nLDL) from healthy subjects, oxidised LDL (oxLDL, formed by oxidation of nLDL) or nLDL from type II diabetic patients (dLDL). 2. Rabbit aortic rings were exposed to nLDL, dLDL or oxLDL (50-200 mg protein l-1), or corresponding vehicle, following which they were constricted with noradrenaline 10(-6) M; concentration-relaxation curves were determined to acetylcholine (ACh), A23187, or sodium nitroprusside (NP), in the absence or presence of L-arginine (10(-5)-10(-3) M), L-ascorbate (10(-5)-10(-3) M) and pyridoxine (0.5-2.0 mM). 3. nLDL, dLDL and oxLDL all inhibited relaxant responses to ACh and A23187, but not to NP, in a concentration-dependent manner (oxLDL>dLDL>nLDL). 4. In the presence of all LDL preparations, L-arginine, L-ascorbate or pyridoxine each improved ACh and A23187 responses, although none completely normalised endothelium-dependent relaxations. The maximal effect of L-arginine occurred at 10(-4) M. The combination of L-arginine 10(-4) M, L-ascorbate 10(-5) M and pyridoxine 2.0 mM was equally effective as L-arginine 10(-4) M alone. 5. Our results confirm that nLDL, dLDL and oxLDL exert inhibitory effects on endothelium dependent, but not endothelium independent, relaxation of rabbit aorta. ACh and A23187 responses in the presence of any LDL species can be ameliorated by supplementation with L-arginine, L-ascorbate or pyridoxine, either singly or in combination, with no agent or combination proving superior to L-arginine alone. Nevertheless, ACh and A23187 responses are not completely normalised with such supplements, suggesting that there also exists a component of LDL-induced inhibition of endothelium-mediated vasorelaxation that is independent of the nitric oxide system.
Adult↗
Aspirin modifies nitric oxide synthase activity in platelets: effects of acute versus chronic aspirin treatment.
OBJECTIVE: We examined the effects of aspirin on basal and beta-adrenoceptor (beta-AR)-mediated nitric oxide synthase (NOS) activity in normal platelets. METHODS: NOS activity was determined from the conversion of L-[3H]arginine to L-[3H]citrulline, both basally and following beta-AR stimulation, in platelets from healthy human subjects following both short- and long-term aspirin administration. RESULTS: Basal L-[3H]citrulline increased following aspirin 800 mg administered intravenously in vivo, from 0.31+/-0.12 to 0.76+/-0.14 pmol/10(8) platelets (P<0.01). Isoproterenol at 1 micromol/l increased platelet NOS activity before but not following intravenous aspirin. After short-term in vitro treatment with aspirin 10 micromol/l, 400 micromol/l or 4 mmol/l, basal platelet L-[3H]citrulline increased similarly, an effect not seen with indomethacin 100 micromol/l or ibuprofen 10 micromol/l. Platelet NOS activity was not increased by albuterol 1 micromol/l, in the presence of indomethacin, ibuprofen or aspirin in vitro. By contrast, oral aspirin 75 mg daily for 14 days did not affect basal platelet NOS activity, but abolished beta-adrenergic NOS activation. CONCLUSIONS: Aspirin activates basal platelet NOS acutely, but not chronically, through a mechanism independent of cyclooxygenase (COX) inhibition. By contrast, both short- and long-term aspirin treatment inhibit platelet beta-adrenergic NOS activation by a COX-dependent mechanism. This indicates that aspirin exerts divergent effects on basal and beta-AR-stimulated platelet NOS activity, which are likely to be of clinical relevance.
Adrenergic beta-Agonists↗
Impairment of vascular endothelial nitric oxide synthase activity by advanced glycation end products.
Endothelial damage is believed to play a key role in the development of both micro- and macrovascular disease in diabetes, and advanced glycation end products (AGEs) may contribute importantly to this. To determine whether glucose-derived AGEs can cause endothelial dysfunction, we examined the effects of albumin AGE-modified by glucose (AGE-Glu) both in vivo, after injection into rabbit femoral artery, and in vitro on rabbit aortic rings and cultured human umbilical vein endothelial cells (HUVEC). Exposure of blood vessels to AGE-Glu, in vivo and in vitro, inhibited endothelium-dependent vasorelaxation, whereas unmodified albumin did not. In isolated rabbit aorta, this effect was reversible after AGE-Glu washout, and the response to the endothelium-independent vasodilator sodium nitroprusside was unaffected by AGE-Glu. In HUVEC, AGE-Glu inhibited endothelial nitric oxide synthase activity, and this was associated with a decrease in serine phosphorylation of this enzyme. Longer term (72 h) incubation decreased HUVEC viability. Use of specific antibodies demonstrated that these effects were mediated by N(epsilon)-(carboxymethyl)lysine (CML), an important AGE found in vivo, and by the AGE-R1 receptor. Furthermore, these effects all occurred at CML concentrations similar to those found in the plasma of diabetic patients. These results suggest an important role of AGE in the pathogenesis of diabetic vasculopathy.
Animals↗
The lipid and non-lipid effects of statins.
The 3-hydroxy-3-methyl glutaryl coenzyme A (HMG-CoA) reductase inhibitors, more commonly known as statins, are a class of drug widely used for the treatment of hypercholesterolaemia in patients with established cardiovascular disease as well as those at high risk of developing atherosclerosis. Their predominant action is to reduce circulating levels of low-density lipoprotein (LDL) cholesterol; to a smaller degree, they also increase high-density lipoprotein (HDL) cholesterol and reduce triglyceride concentrations. In recent years, however, there has been an increasing body of evidence that their effects on lipid profile cannot fully account for their cardiovascular protective actions: their beneficial effects are too rapid to be easily explained by their relatively slow effects on atherogenesis and too large to be accounted for by their relatively small effects on plaque regression. Experimental models have revealed that statins exert a variety of other cardiovascular effects, which would be predicted to be of clinical benefit: they possess anti-inflammatory properties, as evidenced by their ability to reduce the accumulation of inflammatory cells in atherosclerotic plaques; they inhibit vascular smooth muscle cell proliferation, a key event in atherogenesis; they inhibit platelet function, thereby limiting both atherosclerosis and superadded thrombosis; and they improve vascular endothelial function, largely through augmentation of nitric oxide (NO) generation. The relative importance of the lipid- and non-lipid-related effects of the statins in the clinical situation remains the subject of much continuing research.
Animals↗
Renal dopamine receptors and hypertension.
Explore the source record for details and available documents.
Animals↗
Cardiac effects of amiloride and of enalapril in the spontaneously hypertensive rat.
OBJECTIVES: To compare the effects of the sodium-hydrogen exchange blocker, amiloride, with those of the angiotensin-converting enzyme inhibitor, enalapril, on cardiac structure and function and intracardiomyocyte calcium concentration ([Ca2+]i) and pH (pHi), in spontaneously hypertensive rats (SHRs). METHODS: Experiments were performed in SHRs treated for 4 weeks with amiloride 7.5 mg/kg per day, enalapril 6.0 mg/kg per day or vehicle, and in Sprague-Dawley rats (SDRs). After haemodynamic measurements were taken, the heart was removed and weighed and hydroxyproline (a marker of collagen content) was assayed. In separate rats, ventricular myocytes were isolated, their size determined, and [Ca2+]i and pHi examined using fluo-3 acetoxymethyl ester and 2',7'-bis(2-carboxyethyl)-5(6)-carboxyfluorescein tetrakis acetoxymethyl ester fluorescence, respectively. RESULTS: Left ventricular end-diastolic pressure was increased, and the maximal rates of increase and of decrease in pressure with time in the left ventricle were decreased in SHRs compared with SDRs. Myocytes were larger and hydroxyproline was increased in the left ventricle, but not in the right ventricle of SHRs compared with SDRs. Amiloride and enalapril decreased systolic blood pressure in SHRs similarly, and improved diastolic function in these rats, enalapril more than amiloride. Both agents decreased left ventricular myocyte size to similar extents; however, whereas enalapril decreased the left ventricular hydroxyproline content, amiloride did not. Left ventricular myocytes from SHRs exhibited greater [Ca2+]i and pHi than those from SDRs; enalapril decreased [Ca2+]i more than amiloride, but amiloride decreased pHi more than enalapril. CONCLUSIONS: In SHRs, enalapril prevents left ventricular hypertrophy, collagen deposition, diastolic dysfunction, and increases in [Ca2+]i more effectively than does amiloride. In contrast, the latter prevents the increase in pHi more effectively than enalapril, despite similar reductions in blood pressure. These findings suggest that their effects do not depend solely on blood pressure reduction.
Amiloride↗
Effects of beta-adrenoceptor stimulation on endothelial nitric-oxide synthase phosphorylation of human umbilical vein endothelial cells.
AIM: To investigate the effects of isoprenaline on the phosphorylation level of endothelial nitric oxide synthase (eNOS) of human umbilical vein endothelial cells (HUVEC) and to elucidate the regulation mechanisms of beta-adrenoceptor (beta-AR) on eNOS activity. METHODS: HUVEC were exposed to isoprenaline (1 micromol/L) for 30 min, in the absence or presence of selective beta1- or beta2 -adrenoceptor antagonists. eNOS was then isolated by immunoprecipitation using a specific eNOS antibody. eNOS activity was determined by the conversion of L-[3H]arginine to L-[3H]citrulline. The levels of eNOS expression and eNOS phosphorylation were measured by Western blotting. RESULTS: Treatment of HUVEC with isoprenaline (1 micromol/L) for 30 min caused no measureable change in eNOS expression. However, eNOS activity and serine phosphorylation level were significantly increased (P<0.01). This effect could be abolished by a selective beta2-adrenoceptor antagonist ICI 118551. CONCLUSION: Isoprenaline increases eNOS activity of HUVEC, this is mediated by beta2-adrenoceptor and associated with an increase of eNOS serine phosphorylation level.
Adrenergic beta-Agonists↗
Amlodipine, but not verapamil or nifedipine, dilates rabbit femoral artery largely through a nitric oxide- and kinin-dependent mechanism.
1. We investigated the nitric oxide (NO) dependence of vasorelaxation in response to different calcium channel blockers (CCB), in rabbit femoral artery in vivo. 2. Anaesthetized rabbits underwent femoral artery ligation, and blood from the proximal artery was returned distal to the ligature through a constant infusion pump. The effects of local injection of CCB on perfusion pressure and plasma nitrite+nitrate (NO(x), which reflects local NO biosynthesis) concentration in this system were determined. 3. Intra-arterial verapamil, nifedipine or amlodipine 10 micromol x kg(-1) each reduced perfusion pressure. Pre-treatment with intra-arterial N(G)-nitro-L-arginine methyl ester (L-NAME, a NO synthase inhibitor) 1 micromol x kg(-1) did not affect responses to verapamil or nifedipine, but attenuated the reduction in perfusion pressure to amlodipine, from 33.2+/-2.1% to 22.5+/-1.6% (P=0.002). 4. Intra-arterial amlodipine--unlike verapamil or nifedipine--increased femoral venous NO(x), from 9.1+/-0.4 microM to 14.1+/-0.5 microM (P=0.005). 5. The bradykinin B2 receptor antagonist HOE 140, 30 mg x kg(-1), attenuated the reduction in perfusion pressure and abolished the rise in venous NO(x) concentration, following intra-arterial amlodipine. 6. Amlodipine potently inhibited serum angiotensin converting-enzyme (ACE) activity in vitro, as effectively as enalapril at similar concentrations. 7. These results suggest that the vasorelaxant effects of nifedipine and verapamil are NO-independent, whereas those of amlodipine are partly NO-dependent, in rabbit femoral artery in vivo. This effect of amlodipine occurs through B2 receptor activation, and may be related to an increase in local bradykinin through inhibition of ACE.
Amlodipine↗
Statins and vascular protection: a 'radical' view.
Explore the source record for details and available documents.
Animals↗