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Tetrahydrobiopterin improves aging-related impairment of endothelium-dependent vasodilation through increase in nitric oxide production.

Deficiency of tetrahydrobiopterin (BH4), an essential cofactor for nitric oxide (NO) synthase, decreases NO production and increases reactive oxygen species. The purpose of this study was to elucidate the effects of aging on endothelial function and to determine whether the degree of BH4 deficiency is related to aging and oxidative stress. We evaluated forearm blood flow (FBF) responses to acetylcholine (ACh), an endothelium-dependent vasodilator, and isosorbide dinitrate (ISDN), an endothelium-independent vasodilator, before and after co-infusion of BH4 (500 mg/min) in 37 healthy men (mean age, 41+/-18 yr; range, 19-81 yr). FBF was measured using strain-gauge plethysmograph. Urinary 8-hydroxy-2'-deoxyguanosine (8-OHdG) and serum malondialdehyde-modified low-density lipoprotein (MDA-LDL) were measured as indices of oxidative stress. Both ACh and ISDN increased the FBF in a dose-dependent manner in all subjects. Co-infusion of BH4 resulted in a significant increase in ACh-induced vasodilation (from 22.3+/-6.7 to 30.1+/-7.5 mL/min/100 mL tissue, P<0.05). Aging was found to be significantly correlated with ACh-induced vasodilation (r=-0.47, P=0.006), urinary 8-OHdG (r=0.38, P=0.02), serum MDA-LDL (r=0.36, P=0.02), and the change in ACh-induced vasodilation after co-infusion of BH4 (r=0.45, P=0.007). The FBF response to ISDN did not correlate with any parameters. Infusion of N(G)-monomethyl-L-arginine, an NO synthase inhibitor, abolished the BH4-induced enhancement of forearm vasorelaxation evoked by ACh. The increase in FBF after ISDN was not altered by BH4. These findings suggest that a deficiency of BH4 may be involved in the pathogenesis of disturbances in endothelium-dependent vasodilation related to aging through decrease in NO production and increase in oxidative stress.

Acetylcholine↗

[Endoscopic sclerotization of esophageal varices and nitrates in the treatment of portal hypertension with bleeding esophageal varices].

The authors investigated changes of some haemodynamic parameters after sclerotization of oesophageal varices and after administration of isosorbide dinitrate in the preparation Iso Mack retard. Twenty patients with cirrhosis of the liver with oesophageal varices grade 3-4 were treated by endoscopic sclerotization only, while to a second comparable group of cirrhotic patients from the first stage of sclerotization oral Iso Mack retard was administered in daily doses of 80-120 mg, depending on tolerance. The haemodynamic parameters were investigated before the onset of treatment and again after completed sclerotherapy or at least three-month treatment with ISDN. After sclerotization of oesophageal varices the pressure in the portal circulation rises significantly as well as the flow through the portal vein due above all to an accelerated blood flow. On the other hand, ISDN prevents a rise of portal hypertension and leads even to a slight decline which is, however, not associated with a decline of the portal flow. A relative disadvantage is the adverse effect on systemic haemodynamics after large nitrate doses. The decline of the portal pressure caused by the vasodilatating effect of ISDN in the splanchnic and portal area is manifested in a very positive way by reduction of relapses of haemorrhage from oesophageal varices. ISDN may play a positive role in the treatment of portal hypertension with oesophageal varices, during acute haemorrhage as well as in the prevention of relapses of haemorrhage. A particularly favourable procedure is the combination with sclerotherapy of oesophageal varices. None of the procedures leads to reduction of the portal flow and preserves hepatic function.

Blood Pressure↗

Nitroester drug's effects and their antagonistic effects against morphine on human sphincter of Oddi motility.

AIM: To evaluate the effects of nitroester drugs on human sphincter of Oddi (SO) motility and their antagonistic effects against morphine which shows excitatory effect on Oddi's sphincter motility. METHODS: The effects of these drugs on SO were evaluated by means of choledochofiberoscopy manometry. A total of 67 patients having T-tubes after cholecystectomy and choledochotomy were involved in the study, they were randomly divided into glyceryl trinitrate (GTN) group, isosorbide dinitrate (ISDN) group, pentaerythritol tetranitrate (PTN) group, morphine associated with GTN group, morphine associated with ISDN group and morphine associated with PTN group. Basal pressure of Oddi's sphincter (BPOS), amplitude of phasic contractions (SOCA), frequency of phasic contractions (SOF), duration of phasic contractions (SOD), duodenal pressure (DP) and common bile duct pressure (CBDP) were scored and analyzed. Morphine was given intramuscularly while nitroester drugs were applied sublingually. RESULTS: BPOS and SOCA decreased significantly after administration of ISDN and GTN, BPOS reduced from 10.95+/-7.49 mmHg to 5.92+/-4.04 mmHg (P<0.05) evidently after application of PTN. BPOS increased from 7.37+/-5.58 mmHg to 16.60+/-13.87 mmHg, SOCA increased from 54.09+/-38.37 mmHg to 100.70+/-43.51 mmHg, SOF increased from 7.15+/-3.20 mmHg to 10.38+/-2.93 mmHg and CBDP increased 3.75+/-1.95 mmHg to 10.49+/-8.21 mmHg (P<0.01) evidently after injection of morphine. After associated application of ISDN and GTN, the four indications above decreased obviously. As for application associated with PTN, SOCA and SOF decreased separately from 100.64+/-44.99 mmHg to 66.17+/-35.88 mmHg and from 10.70+/-2.76 mmHg to 9.04+/-1.71 mmHg (P<0.05) markedly. CONCLUSION: The regular dose of GTN, ISDN and PTN showed inhibitory effect on SO motility, morphine showed excitatory effect on SO while GTN, ISDN and PTN could antagonize the effect of morphine. Among the three nitroester drugs, the effect of ISDN on SO was most significant.

Adult↗

Effects of a novel calcium channel agonist dihydropyridine analogue, Bay k 8644, on pig coronary artery: biphasic mechanical response and paradoxical potentiation of contraction by diltiazem and nimodipine.

Bay k 8644 is a structural analogue of the 1,4-dihydropyridines whose pharmacological actions on heart and vascular smooth muscle are opposite from those of nifedipine and other similar calcium antagonists. We have examined the action of Bay k 8644 ("calcium channel agonist") on isolated porcine coronary artery rings. The interactions between Bay k 8644 and the vasodilators isosorbide dinitrate (ISDN), diltiazem, and nimodipine were quantitated. Bay k 8644 produced a biphasic, dose-dependent mechanical response, with contraction occurring over the concentration range of 1-350 nM (ED50 = 11.4 nM) and relaxation observed at concentrations greater than 350 nM (IC50 = 5.7 microM). ISDN, diltiazem, and nimodipine relaxed, in a dose-dependent manner, maximal Bay k 8644-induced contractions. When the coronary rings were pretreated for 25-90 min with 80% inhibitory concentrations of these vasodilators, there was little or no effect by ISDN on Bay k 8644-induced contractions; however, there was a surprising potentiation by diltiazem and by nimodipine. Pretreatment of coronary rings with higher concentrations of ISDN or diltiazem caused an inhibition of Bay k 8644-induced contraction, while pretreatment with higher concentrations of nimodipine caused further potentiation of contraction elicited by Bay k 8644. Bay k 8644 increased the tension developed in response to high potassium (potential-operated channel activation) or histamine (receptor-operated channel activation). To account for the biphasic response to Bay k 8644 (dose-dependent contraction and relaxation), and the unexpected potentiation of Bay k 8644-induced contraction by nimodipine and by diltiazem, a molecular model is proposed for vascular smooth muscle in which Bay k 8644 functions as a partial calcium channel agonist at two functionally distinct 1,4-dihydropyridine "receptor sites."

3-Pyridinecarboxylic acid, 1,4-dihydro-2,6-dimethy↗

[Ticlopidine-induced cholestasis].

UNLABELLED: We report a case of ticlopidine-induced cholestatic hepatitis. CASE SUMMARY: An 82-year-old man suffered a myocardial infarction in February 1998. Because of persistent angina pectoris a coronary stent was implanted in May 1998. At this time medication with 1 x 250 mg ticlopidine was started in addition to the preexistent medication of aspirin 1 x 100 per day, metoprolol fumarate 1 x 95 mg per day and isosorbide dinitrate 1 x 100 mg per day. Three weeks after starting ticlopidine the patient complained of itching, and on day 28 painless jaundice developed. At this time, the serum activities of alkaline phosphatase (923 U/l), gamma-GT (823 U/l) and total bilirubin concentration (129 mumol/l) were markedly elevated, whereas the activities of the transaminases (AST 131 U/l, ALT 194 U/l) were slightly increased. An extra- or intrahepatic biliary obstruction was ruled out, and there were no signs of a toxic, infectious or immunological cause for the hepatic injury. Liver biopsy showed centro-acinar cholestasis. After drug discontinuation the itching stopped after 4 weeks and jaundice disappeared after 2 weeks. Eight months after the onset of symptoms, the activities of alkaline phosphatase (226 U/l) and gamma-GT (213 U/l) were still elevated but the patient was asymptomatic. CONCLUSIONS: Ticlopidine-induced mild serum liver enzyme elevations have been observed in some studies (incidence 1-2%). The incidence of severe hepatitis has been estimated at 0.0013%. Only a few cases (in approximately 20 patients receiving ticlopidine) of a severe cholestatic pattern of injury have been reported. In all cases the jaundice resolved and serum liver enzyme concentrations normalised over a period of months. Characteristically, liver biopsies demonstrated centro-acinar cholestasis. Monitoring of serum liver enzyme concentrations is not recommended. When itching or jaundice occur in a patient taking ticlopidine, the possibility of toxic liver damage should be taken into account.

Aged↗

[Effects of isosorbide 5-mononitrate on cardiovascular function. (I). Effects on the left ventricular system].

Effects of isosorbide 5-mononitrate (5-ISMN) on cardiovascular function were compared with those of isosorbide dinitrate (ISDN), verapamil and propranolol. In anesthetized open-chest dogs, intravenous injection of 5-ISMN (1 mg/kg, 3 mg/kg) scarcely decreased cardiac contractile force (CCF) and heart rate (HR). The systolic blood pressure (SBP) fell in a dose-dependent manner, and the degree of the change was greater than that in diastolic blood pressure (DBP). Especially, left ventricular pressure (LVP) and left ventricular dp/dt (LVdp/dt) were significantly decreased, and a considerable reduction in left ventricular end-diastolic pressure (LVEDP) was also observed. Intravenous injection of verapamil (0.3 mg/kg) considerably lowered DBP. While HR, CCF, LVP and LVdp/dt were markedly decreased, LVEDP showed a moderate increase. Propranolol (0.5 mg/kg, i.v.) greatly decreased LVdp/dt together with HR and CCF. Conversely, LVEDP showed a slight increase. There was no change in SBP, DBP and LVP. The vasodilating potency of 5-ISMN was 150 times smaller than that of ISDN on the contractile response in isolated rabbit thoracic aorta. On the other hand, in terms of decrease in pulse pressure, the potency exhibited by 5-ISMN was about 4 times (intravenous administration in anesthetized dogs) or 1.5 times (oral administration in conscious dogs) smaller than that of ISDN. The present results suggest that 5-ISMN shows a high bioavailability and a potency comparable to ISDN, especially in the case of peroral administration. Taking these results together with the fact that transient left ventricular failure occurs during myocardial ischemia into consideration, it is thought that peroral 5-ISMN preparation may be useful in the therapy of angina pectoris.

Animals↗

Impaired modulation of sympathetic excitability by nitric oxide after long-term administration of organic nitrates in pigs.

BACKGROUND: Endogenous nitric oxide (NO) reduces sympathetic vasoconstriction by attenuating neuronal excitability in the brain stem and inhibition of postganglionic neurotransmission. We studied whether this modulation of sympathetic circulatory control by NO may be altered during chronic administration of NO donor drugs in pigs. METHODS AND RESULTS: Nitrate tolerance was induced by oral administration of isosorbide dinitrate (ISDN, 4 mg/kg per day for 4 weeks) in eight pigs. Four of them were chronically instrumented for the measurement of mean arterial blood pressure and cardiac output in the conscious state. ISDN treatment caused hemodynamic tolerance to NO donors and significantly increased the hypotensive responses to pharmacologic ganglionic blockade in conscious pigs. In general anesthesia, ISDN-treated animals and age-matched controls (n=5) had similar baseline renal sympathetic nerve activity and in both groups neither inhibition of NO synthases (NOS) nor administration of NO donors to the brain stem by intracerebroventricular (i.c.v.) infusions caused significant changes in baseline renal sympathetic nerve activity. However, whereas sympathoexcitatory responses to glutamate (0.5 mL, 0.1 mol/L, i.c.v.) or electrical stimulation of somatic nerve afferents were significantly potentiated by central NOS inhibition and attenuated by NO donors in controls, these treatments no longer had significant effects in ISDN-treated pigs. Furthermore, reflex sympathetic activation in response to intravenous NO donor treatment was more pronounced in nitrate tolerant animals, which suggests loss of central sympathoinhibitory effects of NO. Subsequent histology on brain stem slices with NADPH-diaphorase as NOS marker revealed significant reduction of NOS density in ISDN-treated pigs. CONCLUSIONS: Long-term administration of organic nitrates reduces the number of NO-producing neurons in the brain stem and causes loss of inhibitory effects of NO on sympathetic excitability. This component of tolerance to organic nitrates may be important in patients confronted frequently with sympathetic activation caused by mental and/or physical stressors.

Animals↗

Hemodynamic effects of vasodilators and long-term response in heart failure.

Hemodynamic responses to vasodilators are commonly assessed when starting long-term vasodilator treatment in patients with chronic left ventricular failure, although the relation between short- and long-term responses is not established. Thus, short- and long-term hemodynamic responses to placebo and vasodilators (isosorbide dinitrate, minoxidil and enalapril or captopril) were measured and long-term clinical efficacy was assessed by changes in exercise capacity after 1 to 5 months of vasodilator administration (plus digitalis and diuretic agents) in 46 patients with New York Heart Association functional class II to IV heart failure caused by cardiomyopathy. There were no significant changes in hemodynamics or exercise capacity during placebo treatment. After initial doses and during long-term administration of vasodilator drugs, hemodynamics were significantly improved. After long-term vasodilator treatment, maximal oxygen uptake during exercise increased by 2.9 +/- 5.7 ml/min per kg from a control value of 14.1 +/- 5.6 ml/min per kg (p less than 0.01), and exercise duration also increased by 1.8 +/- 3.5 minutes (p less than 0.01). Changes in maximal oxygen uptake, however, did not correlate with short-term changes in pulmonary wedge pressure (correlation coefficient [r] = -0.14), cardiac index (r = -0.01) or systemic vascular resistance (r = -0.20). Long-term hemodynamic changes also failed to correlate with changes in exercise capacity. Baseline hemodynamics, cardiac dimensions and left ventricular ejection fraction before vasodilator administration all failed to correlate with baseline exercise capacity or with long-term changes in exercise capacity. Thus, hemodynamic measurements at initiation or during follow-up of vasodilator therapy do not relate to long-term clinical efficacy assessed by exercise capacity in patients with chronic left ventricular failure. Therefore, the rationale for making invasive hemodynamic measurements before initiating long-term vasodilator therapy for heart failure is questioned.

Antihypertensive Agents↗

Aggressive systematic treatment for central retinal artery occlusion.

PURPOSE: To report the efficacy of an aggressive systematic regimen for the treatment of acute nonarteritic central retinal artery occlusion (CRAO). METHODS: Eleven patients who had unilateral CRAO with symptoms of fewer than 48 hours' duration were treated with an aggressive stepwise systematic regimen until retinal circulation improved or until all the treatment steps were performed. Five patients with unilateral CRAO and symptoms of fewer than 48 hours' duration were treated in the same institution in an arbitrary nonsystematic manner. The therapeutic steps of the aggressive treatment included ocular massage, sublingual isosorbide dinitrate, intravenous acetazolamide, intravenous mannitol or oral glycerol, anterior chamber paracentesis, intravenous methylprednisolone followed by streptokinase, and retrobulbar tolazoline. After each step, retinal flow was evaluated by three-mirror contact lens. The nonsystematic treatment was arbitrary and included one or several of the above. Visual acuity and complete eye examination data were recorded before and after treatment. RESULTS: Visual acuity and retinal arterial supply were improved in eight (73%) of the 11 patients treated in the stepwise systematic manner. All eight patients in whom visual acuity improved had symptoms for fewer than 12 hours, and the presumed cause was either platelet-derived or cholesterol embolus from atheroma or the patients had glaucoma. Patients in whom visual acuity did not improve had CRAO that was attributed to calcified emboli or primary antiphospholipid antibody syndrome and had symptoms more than 12 hours before treatment. Visual acuity did not improve in all five patients with the nonsystematic treatment regardless of the presumed cause or duration of the occlusion. The success of the treatment in the systematic treatment group was statistically significantly better compared with the outcome of the nonsystematic treated group (Fischer exact test, P = .01). CONCLUSIONS: In the treatment of CRAO, an aggressive systematic regimen including medical and mechanical means may reestablish retinal circulation and improve visual outcome. The cause of arterial occlusion, the nature of occlusive emboli, and the duration of retinal ischemia may determine the visual outcome, but a larger series is warranted to verify the effectiveness of the treatment and the prognostic factors.

Acetazolamide↗

Usefulness of twice-daily isosorbide-5-mononitrate in preventing development of tolerance in angina pectoris.

Development of tolerance to nitrates during long-term therapy is a major concern. It has been suggested that isosorbide-5-mononitrate (IS-5MN), an active metabolite of isosorbide dinitrate, administered twice daily 12 hours apart does not lead to development of tolerance. The duration of effects of IS-5MN at a dose of 20 and 40 mg and of placebo was studied in patients with angina pectoris who responded to nitrates after the first dose (n = 12) and after 1 week of twice-daily therapy (n = 9). The study was double-blind, randomized and crossover in design. Compared with placebo values, after the first dose of 20 and 40 mg IS-5MN, exercise duration was higher at 2 hours (p less than 0.001) and 6 hours (p less than 0.02). After 1 week of twice-daily therapy at these doses, exercise duration increased at 2 hours (p less than 0.05) but not at 6 or 10 hours after the dose. After the first dose of 20 and 40 mg IS-5MN, standing systolic blood pressure decreased at 2 hours (p less than 0.02). Blood pressure did not change significantly after chronic therapy. Tolerance to antianginal effects during twice-daily therapy with 20 and 40 mg of IS-5MN developed despite higher plasma IS-5MN concentrations at 2 and 6 hours during twice-daily therapy than after the first dose. The tolerance during twice-daily therapy with IS-5MN was characterized by a reduced peak effect at 2 hours and shortened duration of action compared with first-dose effects.

Aged↗

Retinopathy identifies marked restriction of coronary flow reserve in patients with diabetes mellitus.

OBJECTIVES: This study sought to assess the differences in coronary flow reserve in patients with and without diabetic retinopathy. BACKGROUND: Microvascular abnormalities throughout the body and impairment of coronary flow reserve have been described in patients with diabetes mellitus. However, the relation between diabetic retinopathy and coronary microvascular disease has not been investigated. METHODS: The study included 29 patients with diabetes mellitus (18 with and 11 without diabetic retinopathy) and 15 control patients with chest pain and normal coronary arteries. Diabetic retinopathy was nonproliferative in all 18 patients with this disorder (8 had background, 10 preproliferative retinopathy). Five minutes after injection of 3 mg of isosorbide dinitrate, phasic flow velocities were recorded in the proximal segment of the angiographically normal left anterior descending coronary artery at rest and during hyperemia (0.14 mg/kg body weight per min of adenosine infused intravenously) using a 0.014-in. 15-MHz Doppler guide wire. Coronary blood flow was calculated, and coronary flow reserve was obtained from the hyperemic/baseline flow ratio. RESULTS: Coronary blood flow was significantly lower during hyperemia ([mean +/- SD] 107 +/- 23 and 116 +/- 18 vs. 136 +/- 17 ml/min, respectively) and higher at baseline (58 +/- 16 and 45 +/- 12 vs. 37 +/- 10 ml/min, respectively) in diabetic patients with and without retinopathy than in control subjects (p < 0.05 for both diabetic groups). As a result, coronary flow reserve in both groups of diabetic patients was significantly lower than in control patients (1.9 +/- 0.4 and 2.8 +/- 0.3 vs. 3.3 +/- 0.4, respectively, p < 0.01 for both diabetic groups), and its reduction was greater in patients with than without retinopathy (p < 0.01). Furthermore, in patients with diabetic retinopathy, maximal hyperemic coronary flow (102 +/- 11 vs. 114 +/- 16 ml/min, p < 0.05) and flow reserve (1.6 +/- 0.2 vs. 2.3 +/- 0.2, p < 0.01) were significantly lower in those with preproliferative than background retinopathy. CONCLUSIONS: Coronary flow reserve is significantly restricted in patients with diabetes mellitus, and its reduction is more marked in those with diabetic retinopathy, especially in advanced retinopathy. Thus, diabetic retinopathy should identify marked restriction of coronary flow reserve in patients with diabetes mellitus.

Adult↗

Selective effects of nitric oxide on the disposition of chlorzoxazone and dextromethorphan in isolated perfused rat livers.

The rapid and direct effects of nitric oxide (NO) donors sodium nitroprusside (SNP) and isosorbide dinitrate (ISDN) on the hepatic and biliary disposition of chlorzoxazone (CZX), a marker of CYP2E1, and dextromethorphan (DEM), a marker of CYP2D1, were studied in a single-pass isolated perfused rat liver model. Livers (n = 30) were perfused with constant concentrations of NO donors (0-120 min) in addition to infusion of CZX or DEM (60-120 min), and periodical outlet and bile samples were collected. Both ISDN and SNP significantly reduced (30 and 60%, respectively) the hepatic extraction ratio of CZX and decreased (50 and 70%, respectively) the recovery of the CYP2E1-mediated metabolite, 6-hydroxychlorzoxazone, in the outlet perfusate and bile. As for DEM, both NO donors increased (up to 3.5-fold) the recovery of the CYP2D1-mediated metabolite dextrorphan (DOR) in the outlet perfusate. However, this was associated with a simultaneous decrease (50-75%) in the excretion of the metabolite into the bile, thus resulting in no change in the overall recovery of DOR as a result of NO donor treatment. The decrease in the biliary excretion of DOR was caused by NO-induced simultaneous reductions in both the conjugation of DOR and biliary clearance of DOR conjugate. Additionally, both SNP and ISDN significantly reduced the metabolism of DEM to 3-hydroxymorphinan, which is mostly regulated by CYP3A2. These studies in an intact liver model confirm the selectivity of the inhibitory effects of NO donors on cytochrome P450 enzymes, which was recently reported in microsomal studies, and expand these inhibitory effects to conjugation pathways.

Alcohol Oxidoreductases↗

Ambulatory long-term vasodilator therapy for chronic refractory heart failure: hemodynamic evaluation and clinical response.

We evaluated long-term combined vasodilator therapy (hydralazine or ecarazine + isosorbide dinitrate) in 29 patients with chronic congestive heart failure resistant to the optimal conventional therapy. There were 24 men and 5 women, aged 28 to 76 years (mean 52 y/o). The etiology of heart failure was congestive cardiomyopathy in 24 patients, ischemic cardiomyopathy in 4 patients and advanced mitral regurgitation due to calcified mitral annulus in 1 patient. There were 21 patients in NYHA class III and 8 patients in NYHA class IV. All patients continued their previous therapeutic regimen during the period of this study. Hemodynamic measurements were performed with a triple lumen flow-directed balloon-tipped catheter in 20 patients to evaluate the effects of vasodilator therapy. In the rest of 9 patients, heart rate, blood pressure, chest X-ray examination for heart size (CTR) and M-mode echocardiograms for ejection fraction (EF) were monitored. The hemodynamic responses to the combined vasodilator therapy in 20 patients showed significant decreases in afterload and preload concomitant with an increase in cardiac output. The noninvasive evaluation of combined vasodilator therapy in 9 patients resulted in significant improvement in CTR and EF. We also noted a significant improvement in their symptoms of 29 patients. Side effects and drug toxicity were uncommon during vasodilator therapy. It is concluded that the combined vasodilator therapy is most useful adjunctive therapy in the management of severe refractory heart failure. Moreover, long-term nonparenteral vasodilators can be administered even at outpatient clinic without hemodynamic monitoring.

Adult↗

The insufficient nitrate response: patients' characterization and response to beta and calcium blockade.

Little information has been published regarding the nitrate-induced changes of left ventricular volumes at rest and during exercise in relation to the degree of the anti-ischaemic response. Therefore we assessed the electrocardiographically defined nitrate response to a single tablet of 80 mg isosorbide dinitrate s.r. and compared it to the changes in end-diastolic volumes at rest and during exercise, as determined by radionuclide ventriculography. Thirty-four of the 63 patients were classified as good nitrate responders, whereas 29 patients showed insufficient nitrate response with regard to the reduction of exercise-induced ST-segment depression. The baseline characteristics were quite comparable. At rest the ISDN-induced decrease of the end-diastolic count rate was significantly less (-17%) in patients with insufficient ST-segment response when compared to patients with good ST-segment response (-25%). During exercise, in patients with good ST-segment response, ISDN reduced the end-diastolic volume significantly (-19%), whereas in patients with insufficient ST-segment response the end-diastolic volume remained unchanged. In this special subset of patients with insufficient nitrate response we further evaluated the effects of additional beta or/and calcium blockade. The benefits from verapamil were equivalent to propranolol. However, a considerable part of the patients investigated needed the combination of verapamil and propranolol for an optimal anti-ischaemic drug treatment. Thus, our data support the concept that preload reduction plays a major role for the anti-ischaemic effects of ISDN in patients with exercise-dependent ischaemia. Since, a suboptimal therapeutic effect must be considered, objective control of the nitrate therapy (usually by exercise- and Holter-ECG) must be regarded as obligatory for each individual patient if optimal results are to be expected.

Adult↗

Hemodynamic effects of nitroglycerin and long-acting nitrates.

Nitroglycerin (NTG) and isosorbide dinitrate (ISDN) are potent dilators of vascular smooth muscle. The organic nitrates produce venodilation at very low doses, with little additional vasodilation of the venous circulation with increasing dosage. Nitrates increase arterial diameter and improve arterial conductance at low to moderate doses, and at high doses these agents produce dilation of the arteriolar or resistance vessels of the body. The overall hemodynamic response to nitrate administration will be modulated by the degree of sympathetic reflex discharge, the presence or absence of congestive heart failure, the dosage of administered nitrate, and the presence or absence of nitrate tolerance. Regional circulatory effects of the organic nitrates include a decrease in vascular resistance and an increase in arterial blood flow to the arms and legs. Venodilation also occurs in the extremities. In the splanchnic and mesenteric circulations, nitrates induce an initial vasodilative response followed by reflex vasoconstriction. Hepatic blood flow changes little in the normal state. Pulmonary blood flow decreases and pulmonary artery and venous pressures fall after nitrate administration. Renal blood flow remains essentially unchanged or decreases slightly after NTG administration, although reflex sympathetic activity may cause secondary vasoconstriction. The antianginal effects of nitrates have long been thought to be related to their systemic or peripheral actions, which reduce myocardial oxygen requirements through decreases in left ventricular preload and afterload. There is, however, considerable evidence that nitrates have important direct effects on the coronary circulation in both the normal and the ischemic heart. Such actions include coronary artery dilation, increased collateral blood flow, and enhanced oxygenation and nutrient perfusion to zones of ischemia.(ABSTRACT TRUNCATED AT 250 WORDS)

Angina Pectoris↗

Myocardial protective effects of nicorandil during percutaneous coronary intervention in patients with unstable angina.

BACKGROUND: The purpose of the study was to prospectively evaluate the protective effect of nicorandil during percutaneous coronary intervention (PCI) in patients with unstable angina (UAP). METHODS AND RESULTS: Two hundred patients (61+/-10 year-old, male 143) diagnosed with UAP at an emergency medical center were randomly assigned to 2 groups: intravenous isosorbide dinitrate, Group I (n=100), or intravenous nicorandil, Group II (n=100). PCI was performed 12-48 h after infusion of each agent. Serum concentrations of creatine kinase-MB (CK-MB), cardiac troponin T (cTnT), and I (cTnI) were measured before and 6, 12, 24 h after PCI. Patients with non-coronary chest pain, requiring emergency coronary angiogram, temporary pacemaker or glycoprotein IIb/IIIa receptor blocker were excluded. PCI was successfully performed in 96 patients (Group I=54, 61.7+/-8.2 years, 32 males; Group II=42, 60.4+/-11.7 years, 27 males). No significant differences in clinical or coronary angiographic characteristics were observed between the 2 groups. The concentration of CK-MB was elevated in 9 patients (17%) of Group I and 6 (14%) of Group II, cTnT in 16 (30%), 6 (14%) and cTnI in 25 (46%), 9 (21%) after PCI. Elevation of any troponin was less frequent in Group II [28/54 (52%) vs 10/42 (24%) patients, p=0.01]. Major adverse coronary events during the 6-month clinical follow-up occurred in 9 (17%) of Group I and 5 patients of Group II (12%, p=NS). Follow-up echocardiography revealed lower left ventricular ejection fraction in Group I than in Group II (65.4+/-7.2% vs 71.0+/-6.7%, p=0.03). CONCLUSION: Nicorandil has a myocardial protective effect during PCI in patients with UAP.

Aged↗

Duration of effects and tolerance of slow-release isosorbide-5-mononitrate for angina pectoris.

Isosorbide-5-mononitrate (IS-5MN) is an active metabolite of isosorbide dinitrate, but unlike its parent compound, is nearly 100% bioavailable after oral administration. Once-a-day therapy with a slow-release formulation of IS-5MN is used widely in Europe for 24-hour prophylaxis of angina pectoris. In a randomized, crossover, double-blind, placebo-controlled study, the duration of effects of 50 and 100 mg of slow-release IS-5MN were evaluated after the first dose and after once-a-day therapy for 1 week in 9 patients with stable angina pectoris. Compared with placebo values, standing blood pressure decreased (p less than 0.001) and exercise time to the onset of angina and total exercise duration increased (p less than 0.008 and p less than 0.003) at 4 hours, but not at 20 or 24 hours after first dose of 50 and 100 mg of slow-release IS-5MN. After once-a-day therapy for 1 week, no improvement in exercise duration or reduction in ST-segment depression was seen after 50 or 100 mg of slow-release IS-5MN at 4, 20 or 24 hours despite high plasma IS-5MN concentrations. Thus, despite therapeutic plasma concentrations, 50 and 100 mg of slow-release IS-5MN did not exert antianginal or anti-ischemic effects at 20 and 24 hours after the first dose and at 4, 20 and 24 hours after sustained once-a-day therapy for 1 week.

Adult↗

Hemodynamic comparison of primary venous or arteriolar dilatation and the subsequent effect of furosemide in left ventricular failure after acute myocardial infarction.

The hemodynamic effect of venous dilatation (intravenous isosorbide dinitrate [ISDN]) and arteriolar dilatation (intravenous hydralazine), both as firstline treatment and then combined with intravenous furosemide, were evaluated in a randomized, between-group comparison in 20 men with severe acute left-sided cardiac failure after myocardial infarction (MI). Both ISDN (50 to 200 micrograms/kg/hour) (Group 1) and hydralazine (0.15 mg/kg) (Group 2) reduced systemic arterial pressure (p less than 0.05) and vascular resistance (p less than 0.05). Pulmonary artery occluded pressure was reduced (p less than 0.01) only by ISDN, whereas heart rate (p less than 0.01), cardiac output (p less than 0.01) and stroke volume (p less than 0.05) were increased only after hydralazine. After ISDN, furosemide (1 mg/kg) decreased left-sided cardiac filling pressure by 1 mm Hg (p greater than 0.05), whereas after hydralazine, furosemide in a similar dose reduced pulmonary artery occluded pressure by 5 mm Hg (p less than 0.01). In both groups of patients, furosemide transiently increased systemic arterial pressure (p less than 0.05). Cardiac output was reduced (p less than 0.05) and systemic vascular resistance increased (p less than 0.05) in Group 1 patients after furosemide. Similar changes in both variables in Group 2 patients did not attain statistical significance. In conclusion, ISDN-induced venous dilatation is preferable to primary arteriolar dilatation by hydralazine as first-line treatment in acute left-sided cardiac failure. However, hydralazine and furosemide in combination were equally effective in reducing pulmonary artery occluded pressure and increasing cardiac output. The influences of each regimen on prognosis await further investigation.

Adult↗