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PubMed1985

Aspirin or dipyridamole individually prevent lipid accumulation in primate vein bypass grafts.

Although platelet inhibition with both aspirin and dipyridamole is widely prescribed for patients with coronary artery bypass grafts, data are lacking to prove that combined drug therapy has greater efficacy in preserving graft integrity than either drug given independently. Thus, the ability of combined vs single drug therapy to reduce cholesterol and apolipoprotein-B accumulation were compared in autologous cephalic veins grafted into femoral arteries of 23 stump-tailed macaque monkeys. Ten monkeys were studied in 2 phases. They were treated with aspirin (80 mg/day) during 1 phase and with dipyridamole (50 mg/day) during the other phase. Five monkeys received aspirin plus dipyridamole in combination and 8 received no medication and served as controls. When grafts were removed 3 months after insertion cholesterol and apolipoprotein-B concentrations in grafts were similar for groups treated with aspirin, with dipyridamole, and with the drugs combined, and in each of the treated groups these concentrations were significantly reduced compared with grafts from untreated control monkeys. Cholesterol and apolipoprotein-B concentrations in grafts from the treated groups were similar to concentrations in normal ungrafted veins, whereas cholesterol and apolipoprotein-B levels in grafts from control monkeys were significantly greater than those in ungrafted veins (250% and 925% of normal, respectively). Our findings reaffirm the ameliorative effect of anti-platelet drugs in reducing the accumulation of lipid in vein bypass grafts and indicate that the efficacy of aspirin or dipyridamole given individually equals that of the combination of these drugs in this subhuman primate model. The relation of the lipid-lowering effect of these agents to their antithrombotic effect is uncertain.

Animals↗
PubMed1985

Dipyridamole-echocardiography test in effort angina pectoris.

This study assesses the clinical feasibility and usefulness of dipyridamole infusion for the detection of coronary artery disease (CAD) by using 2-dimensional echocardiography (2-D echo) and 12-lead electrocardiographic monitoring. Dipyridamole infusion (0.14 mg/kg/min for 4 minutes) was performed in 66 consecutive patients with effort chest pain and in 9 control subjects. Among the 28 patients with positive dipyridamole-echocardiography test responses, 18 had diagnostic electrocardiographic changes (ST-segment depression on anterolateral leads), but these changes were unrelated to the site of asynergy. The dipyridamole-echocardiography test had an overall sensitivity of 56% and specificity of 100% for the presence of CAD. Exercise stress testing (EST) had an overall sensitivity of 62% and a specificity of 80%. Thus, the dipyridamole-echocardiography test, which is feasible in essentially all patients with good basal echocardiograms, has a lower overall sensitivity in detecting CAD than EST but a higher specificity, detects the site of apparent ischemia as identified by regional asynergy more precisely than EST, and can unmask electrocardiographically silent effort ischemia.

Adult↗
PubMed1988

Doppler and two-dimensional echocardiographic assessment of left ventricular function before and after intravenous dipyridamole stress testing for detection of coronary artery disease.

Thallium perfusion imaging following the intravenous infusion of dipyridamole, a potent coronary vasodilator, has been demonstrated to be useful in the evaluation of the functional significance of coronary artery disease (CAD). While recent studies have demonstrated that 2-dimensional echocardiographic monitoring of left ventricular (LV) function after intravenous dipyridamole has a sensitivity somewhat less than that of thallium perfusion imaging, none has examined the usefulness of Doppler evaluation of aortic blood flow in this setting. One hundred patients undergoing dipyridamole-thallium imaging for clinical indications were studied. Technically adequate Doppler echocardiographic studies were obtained in 97 patients. LV ejection fraction, peak aortic velocity and acceleration, as well as segmental LV wall motion, were analyzed before and at peak dipyridamole effect. Thallium perfusion images were normal in 41 and abnormal in 53 patients studied. A statistically significant difference in percent change from baseline to peak dipyridamole effect in velocity, acceleration and ejection fraction was seen between the 2 groups (26 vs -2%, 51 vs -2% and 16 vs 4%, respectively, all p less than 0.05). Comparison of 2-dimensional wall motion analysis to thallium yielded a sensitivity and specificity of 74 and 80%, respectively. In the group of patients who underwent cardiac catheterization, 2-dimensional wall motion analysis yielded a sensitivity of 64% in the detection of CAD. The combination of 2-dimensional and Doppler echocardiographic parameters increased the sensitivity in the detection of CAD to 85%.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1988

Diagnostic value for coronary artery disease of chest pain during dipyridamole-thallium stress testing.

Intravenous dipyridamole with thallium imaging permits stress testing for coronary artery disease (CAD) without exercise. Chest pain may occur with dipyridamole-thallium testing, but its diagnostic significance is uncertain. Forty-five patients who had coronary angiography, no revascularization and chest pain during dipyridamole-thallium testing were identified. These patients were matched blindly by sex and age to 45 patients who had coronary angiography, no revascularization and no chest pain reported during the dipyridamole-thallium test. In the groups with versus without chest pain, 9 versus 24% had no CAD, 16 versus 16% had 1-vessel disease, 38 versus 29% had 2-vessel CAD and 38 versus 29% had 3-vessel CAD. These differences did not achieve statistical significance. Also, there were no evident differences in the severity of angiographic CAD by vessel or by percent of stenosis (p greater than 0.50). There was only a moderate association with ischemic ST changes (40 versus 16%, p less than 0.02). Chest pain with concurrent ischemic ST changes also failed to predict any difference in distribution or severity of angiographic stenoses. We conclude that chest pain during dipyridamole-thallium testing is not closely related to the severity of CAD and has little diagnostic value.

Adult↗
PubMed1989

Quantitative comparison of thallium-201 scintigraphy after exercise and dipyridamole in coronary artery disease.

Data comparing myocardial thallium-201 imaging after exercise and intravenous dipyridamole infusion in the same patients are scarce. Accordingly, this study is a segment-by-segment quantitative analysis of regional uptake and washout of thallium-201 after dipyridamole (0.56 mg/kg) and symptom-limited exercise testing in 21 patients (ages 58 +/- 9.2 years) with chest pain studied 2.5 +/- 1.0 weeks apart. Thallium-201 activity in 9 myocardial segments was measured in initial and delayed anterior and 45 degree left anterior oblique views, producing 184 pairs of segments in the distribution of 63 coronary supply regions for direct comparison. The number of segments with normal thallium-201 uptake and the number of numerically significant defects were similar with exercise and dipyridamole (76 vs 73%, 24 vs 27%, respectively, difference not significant). A slightly higher proportion of redistribution defects was found after dipyridamole infusion compared to exercise (17 vs 10%, p less than 0.05). Agreement between 87% (165 of 189) of segment pairs was found when each was classified as either normal or abnormal. Although 24 of 189 segments were discordant, agreement was observed in 92% (61 of 63) of coronary supply regions determined to be normal (41 of 41) or abnormal (20 of 22). In 15 patients who underwent cardiac catheterization, exercise and dipyridamole-thallium-201 scintigraphy detected 61% (16 of 26) vs 61% (16 of 26) of stenoses greater than 50% (difference not significant) and 100% (19 of 19) vs 100% (19 of 19) (difference not significant) normal vessels, respectively.(ABSTRACT TRUNCATED AT 250 WORDS)

Coronary Disease↗
PubMed1990

Comparison of early exercise treadmill test and oral dipyridamole thallium-201 tomography for the identification of jeopardized myocardium in patients receiving thrombolytic therapy for acute Q-wave myocardial infarction.

Thrombolytic therapy has become the treatment of choice for patients with acute myocardial infarction. Researchers are not yet able to identify patients with salvage of myocardium who are at risk for recurrent coronary events. Thus, a prospective trial was performed in 46 patients with myocardial infarction (28 anterior and 18 inferior) who received thrombolytic therapy to determine if early thallium tomography (4.7 days) using oral dipyridamole would identify more patients with residual ischemia than early symptom-limited exercise treadmill tests (5.5 days). There were no complications during the exercise treadmill tests or oral dipyridamole thallium tomography. Mean duration of exercise was 11 +/- 3 minutes and the peak heart rate was 126 beats/min. Thirteen patients had positive test results. After oral dipyridamole all patients had abnormal thallium uptake on the early images. Positive scans with partial "filling in" of the initial perfusion defects were evident in 34 patients. Angina developed in 13 patients and was easily reversed with intravenous aminophylline. Both symptom-limited exercise treadmill tests and thallium tomography using oral dipyridamole were safely performed early after myocardial infarction in patients receiving thrombolytic therapy. Thallium tomography identified more patients with residual ischemia than exercise treadmill tests (74 vs 28%). Further studies are required to determine whether the results of thallium tomography after oral dipyridamole can be used to optimize patient management and eliminate the need for coronary angiography in some patients.

Adult↗
PubMed1990

Prognostic value of intravenous dipyridamole thallium imaging in patients with diabetes mellitus considered for renal transplantation.

Patients with diabetes and end-stage renal failure are known to have a high risk for cardiac morbidity and mortality associated with renal transplantation. The most efficient method to determine preoperative cardiac risk has not been established. To determine the effectiveness of intravenous dipyridamole thallium imaging in predicting cardiac events, 40 diabetic renal transplant candidates were studied preoperatively in a prospective trial. The study group consisted of 40 patients whose average age was 42 years (range 27 to 64); 34 (85%) were hypertensive and 21 (53%) were cigarette smokers. Cardiac history included chest pain in 6 patients and prior myocardial infarction in 3 patients. Dipyridamole thallium imaging showed reversible defects in 9 patients, fixed defects in 8 patients and normal scans in 23 patients. Dipyridamole thallium imaging was performed using 0.56 mg/kg of dipyridamole infused intravenously over 4 minutes. Cardiac events occurred only in patients with reversible thallium defects, of which there were 6. Of these 6 patients, 3 had cardiac events before transplantation and 3 had them in the early postoperative phase (within 6 weeks of surgery). Of 21 patients who underwent renal transplantation, 3 had cardiac events within 6 weeks of transplantation. The average duration of follow-up was 11 months (range 1 to 21). Thus, dipyridamole thallium imaging is an effective method of identifying renal transplant candidates likely to develop cardiac complications. Routine coronary angiography may not be necessary to screen all renal transplant candidates for coronary artery disease before surgery.

Adult↗
PubMed1990

Usefulness of the dipyridamole-Doppler test for diagnosis of coronary artery disease.

Two-dimensional and Doppler echocardiographic studies and a hemodynamic investigation were performed during dipyridamole testing in 42 subjects (13 control subjects and 29 patients with coronary artery disease [CAD]), to evaluate the ability of dipyridamole Doppler echocardiography in identifying patients with ischemic left ventricular dysfunction. In the control group, after dipyridamole infusion, Doppler-derived parameters increased significantly from baseline (p less than 0.001). In patients with CAD, peak flow velocity, flow velocity integral and stroke volume failed to increase after dipyridamole infusion (0.89 +/- 0.21 to 0.85 +/- 0.18 m/s, difference not significant; 14 +/- 3 to 12 +/- 4 cm, difference not significant, and 56 +/- 13 to 50 +/- 14 ml/beat, p less than 0.05, respectively). Heart rate, rate pressure product, systemic vascular resistance and mean right atrial pressure had similar variations in the 2 groups. Changes in the 3 Doppler-derived parameters are closely related to the variations of peak positive dP/dt, stroke volume (thermodilution) and left ventricular end-diastolic pressure and are closely related to the coronary angiography jeopardy score and to the appearance of wall motion abnormalities. Thus, by combining Doppler and 2-dimensional echocardiography, dipyridamole-induced myocardial ischemia may be detected in a high percentage of CAD patients, providing a sensitive tool for identifying patients with high-risk coronary artery anatomy.

Adult↗
PubMed1991

Improved specificity of myocardial thallium-201 single-photon emission computed tomography in patients with left bundle branch block by dipyridamole.

Reduced septal uptake of thallium-201 during exercise is frequently observed in patients with left bundle branch block (LBBB) and normal coronary arteries. This may reflect normal coronary autoregulation in response to lower septal oxygen demand; thus, dipyridamole, which uniformly exploits flow reserve, would be more accurate for diagnosis of coronary artery disease (CAD). Sixteen patients with LBBB underwent exercise and dipyridamole thallium-201 single-photon emission computed tomography and coronary angiography within 3 months. Sensitivity for detection of left anterior descending CAD (greater than 50% stenosis) was 0.83 for exercise and 1.00 for dipyridamole. Specificity was 0.30 (visual) or 0.20 (quantitative analysis) for exercise and 0.80 (visual) or 0.90 (quantitative) for dipyridamole (p less than 0.05). Dipyridamole combined with quantitative analysis also improved specificity of CAD detection overall (p less than 0.01). These data demonstrate that pharmacologic vasodilation is more accurate than exercise when diagnosing CAD by myocardial perfusion scintigraphy in patients with LBBB.

Aged↗
PubMed1992

Pulmonary thallium-201 uptake following dipyridamole-exercise combination compared with single modality stress testing.

Angiographic and clinical determinants of pulmonary uptake of thallium-201 were assessed in a laboratory setting where supine bicycle exercise is used for stress testing in the absence of limiting pharmacologic or physical factors, and where symptom-limited exercise is added to intravenous dipyridamole infusion in other cases. Angiographic correlation was available in 400 patients, including 130 tested with exercise, 94 in whom only handgrip or abbreviated bicycle exercise could be used after dipyridamole, and 176 in whom intravenous dipyridamole was combined with a significant level of exercise. For each test mode, lung/myocardial ratios on the immediate image were highly correlated (p less than or equal to 0.001) with a score based on the number of critical coronary artery stenoses, with grading by contrast ventriculography, and with the number of stenosed (greater than or equal to 50%) arteries; relationships (p less than 0.05) to history of myocardial infarction and to gender were also present. Multiple regression analysis showed the critical stenosis score and ventricular dysfunction to be the only significant determinants. When dipyridamole based tests were compared with exercise, curves of receiver-operating characteristics showed a tendency to better diagnostic performance. When dipyridamole is incorporated in stress testing, the value of increased lung uptake as an ancillary diagnostic sign is similar to that established for exercise.

Analysis of Variance↗
PubMed1992

Identification of viable myocardium by dipyridamole-induced improvement in regional left ventricular function assessed by echocardiography in myocardial infarction and comparison with thallium scintigraphy at rest.

In patients with coronary artery disease and left ventricular impairment, the distinction between ventricular dysfunction due to myocardial fibrosis and postischemic, viable, although dys-synergic, myocardium has important clinical implications. Experimental studies have shown that dipyridamole can increase myocardial function in stunned segments, outlining a potential role of dipyridamole-induced functional recovery as an ultrasonic marker of myocardial viability. The aim of this study was to assess whether the increase of regional left ventricular function early during dipyridamole infusion in basally asynergic segments could identify viable myocardium recognized by rest injected, delayed (greater than 14 hours from tracer injection) thallium and (in a subset of patients) late functional recovery evaluated by a follow-up echocardiogram at rest. Twenty-two patients with angiographically documented coronary artery disease and regional dysfunction in resting conditions (average left ventricular ejection fraction 43 +/- 8%) were studied by echocardiography. All patients underwent a dipyridamole-echocardiographic test (up to 0.84 mg/kg over 10 minutes) and a delayed planar thallium study. A 13-segment model was used for both techniques. A score index ranging from 1 (normokinesia) to 4 (dyskinesia) was used for echocardiography. Thallium-201 activity was expressed in each segment as the percentage of maximal activity in the corresponding view. After dipyridamole, the wall motion score was assigned to each segment in resting conditions and at peak hyperkinesia before possible mechanical signs of ischemia.(ABSTRACT TRUNCATED AT 250 WORDS)

Coronary Angiography↗
PubMed1992

Comparison between technetium-99m-teboroxime and thallium-201 dipyridamole planar myocardial perfusion imaging in detection of coronary artery disease.

Technetium-99m (TC-99m)-teboroxime is a new myocardial perfusion imaging agent. The purpose of this prospective study was to compare Tc-99m-teboroxime with thallium-201 imaging after the administration of dipyridamole. Thirty patients referred for the evaluation of chest pain were studied with both thallium-201 and Tc-99m-teboroxime dipyridamole scans (mean interval 2 days). Dipyridamole was administered at 0.142 mg/kg/min for 4 minutes. Planar imaging (3 standard views) was obtained at 5 and 240 minutes after the injection of 2.2 mCi of thallium-201. Tc-99m-teboroxime (18 to 25 mCi) was injected after dipyridamole infusion. A second injection, at rest, was repeated 4 hours later. Planar imaging (3 standard views of 1 minute/view for the first 2 views, and 90 seconds for the last view) was obtained 2 minutes after Tc-99m-teboroxime injection. Blinded reading was performed by 3 observers. Thallium-201 showed perfusion defects in 182 myocardial segments corresponding to 33 of 45 (73%) significantly stenosed coronary arteries (greater than or equal to 70% reduction in endoluminal diameter), and Tc-99m-teboroxime detected 160 abnormal segments corresponding to 29 of 45 (64%) stenosed arteries. Thallium-201 and Tc-99m-teboroxime studies were normal in 3 patients. In conclusion, this study shows that there is a good correlation in the imaging results found with thallium-201 and Tc-99m-teboroxime using dipyridamole infusion on both a segmental and a diagnostic comparison.

Adult↗
PubMed1992

Comparison of accuracy for detecting coronary artery disease and side-effect profile of dipyridamole thallium-201 myocardial perfusion imaging in women versus men.

Intravenous dipyridamole planar thallium-201 imaging is a safe and effective test for detection and prognosis of coronary artery disease (CAD) in the general population. The relative diagnostic accuracy and side-effect profile of dipyridamole thallium-201 stress imaging in women is not defined. Forty-three consecutive female and 71 male patients who underwent dipyridamole thallium-201 imaging (0.56 mg/kg) within 3 months of cardiac catheterization were studied. Scans were considered abnormal if fixed or reversible perfusion defects were detected. Stenosis severity of greater than or equal to 50% luminal diameter reduction of any artery defined CAD. Overall sensitivity for detection of CAD was 0.87 in women and 0.94 in men; specificity was 0.58 in women and 0.63 in men (p = not significant). Sensitivity for detection of 1-vessel CAD was 0.60 in women and 0.94 in men (p = 0.001). The sensitivity for detection of multivessel CAD (with or without surgical revascularization) was 1.0 and 0.94 in women and men, respectively. Adverse effects were reported in 62% of women and in 38% of men (p = 0.01). There was no significant difference in the incidences of chest pain, headache, nausea, flushing or electrocardiographic changes. The incidences of severe ischemia and dizziness were higher in women. Possible explanations for this difference in adverse effects include gender differences in the volume of distribution of dipyridamole due to varied fat-to-muscle ratios and different subjective nocioceptive sensitivities to the effects of dipyridamole. Overall sensitivity and specificity are comparable between the sexes.

Chi-Square Distribution↗
PubMed1994

Hemodynamic and metabolic correlates of dipyridamole-induced myocardial thallium-201 perfusion abnormalities in multivessel coronary artery disease.

The mechanisms responsible for the development of reversible thallium-201 (TI-201) defects with dipyridamole stress in patients with coronary artery disease (CAD) is not well understood. Previous experimental animal studies have demonstrated coronary steal characterized by an absolute decrease in subendocardial flow distal to a stenosis in response to dipyridamole infusion. Accordingly, the purpose of this study was to determine if reversible TI-201 defects in response to dipyridamole infusion are reflective of myocardial ischemia or secondary to regional differences in flow reserve. Dipyridamole (0.56 mg/kg) TI-201 imaging was performed in 23 patients in whom serial electrocardiographic, hemodynamic, aortic and coronary sinus lactate, and coronary sinus adenosine measurements were obtained. All patients with CAD had TI-201 redistribution (3.8 +/- 2.0 defects/patient), and all patients without CAD had normal scans. Mean aortic pressure was similar in both groups and did not change in response to dipyridamole (non-CAD 103 +/- 11 vs CAD 99 +/- 15 mm Hg, p = NS). Pulmonary capillary wedge pressure was similar at baseline (non-CAD 11 +/- 4 vs CAD 13 +/- 5 mm Hg, p = NS) and did not change in response to the drug (non-CAD 14 +/- 3 vs CAD 15 +/- 7 mm Hg, p = NS). Lactate extraction fraction was similar at baseline (non-CAD 0.22 +/- 0.09 vs CAD 0.17 +/- 0.14, p = NS) and decreased similarly in both groups (non-CAD 0.08 +/- 0.06 vs CAD 0.05 +/- 0.12, p = NS).(ABSTRACT TRUNCATED AT 250 WORDS)

Adenosine↗
PubMed1985

Role of adenosine uptake and metabolism by blood cells in the antiplatelet actions of dipyridamole, dilazep and nitrobenzylthioinosine.

Adenosine (Ado, 10 microM) did not inhibit ADP-induced human platelet aggregation in whole blood. However, if the blood was preincubated with dipyridamole (10 microM), a potent inhibitor of the erythrocytic nucleoside transport system (NTS), Ado acted as a strong inhibitor of platelet aggregation. Similarly, Ado inhibited platelet aggregation in whole blood in the presence of other potent NTS inhibitors, dilazep (1 microM) and p-nitrobenzylthioinosine (NBMPR, 1 microM). RA 233 (10 microM), an analog of dipyridamole which is a potent inhibitor of platelet cAMP phosphodiesterase (PDE), did not evoke the Ado effect in whole blood. However, in platelet-rich plasma (PRP), RA 233 potentiated strongly Ado-mediated inhibition, whereas dipyridamole, dilazep and NBMPR were without activity. 5'-Methylthioadenosine (MTA), an Ado receptor antagonist, reversed the inhibition produced by a nucleoside transport system inhibitor plus Ado in whole blood. Dipyridamole (10 microM), dilazep (1 microM) or NBMPR (1 microM) blocked [14C]Ado (10 microM) uptake by blood cells in whole blood, whereas RA 233 (10 microM) was not effective. The combination of 2'-deoxycoformycin (dCF, 5 microM), a tight-binding inhibitor of adenosine deaminase (ADA), plus 5-iodotubercidin (ITu, 10 microM), a potent inhibitor of adenosine kinase (Ado kinase), gave comparable Ado-mediated inhibition of platelet aggregation in whole blood as was obtained when the blood was pretreated with dilazep. These studies suggest that the in vivo antiplatelet actions of drugs such as dipyridamole and dilazep result from their abilities to block erythrocytic Ado uptake and subsequent metabolism, thus elevating the extracellular steady-state concentration of the physiologically occurring, antiplatelet agent, Ado.

Adenosine↗
PubMed1986

Dipyridamole and vascular prostacyclin production.

The action of dipyridamole on the vascular production of prostacyclin (PGI2) has been investigated. Dipyridamole (1-100 microM) did not induce a significant stimulation of PGI2 release in any of the following experimental models: rings of rabbit aorta, cultured endothelial cells from bovine aorta or human umbilical vein, cultured explants of bovine aortic smooth muscle. The activity of known stimuli of PGI2 release (ADP, suloctidil, serotonin) and the capacity of dipyridamole to inhibit adenosine uptake into endothelial cells were carefully checked. Pretreatment of the rabbit aorta with dipyridamole (10-100 microM) prolonged the transient stimulation of PGI2 release induced by mechanical deendothelialization: this effect was probably due to a partial protection of the cyclooxygenase against oxidative self-inactivation. Our largely negative results are consistent with the current theory that the antiplatelet action of dipyridamole is mediated by adenosine and not by PGI2.

Adenosine↗
PubMed1983

Dipyridamole inhibition of adenosine metabolism in human blood.

The effects of dipyridamole on the metabolism of adenosine were studied in human whole blood. The half-life for adenosine disappearance and the formation of deamination and phosphorylation products were determined by adding [3H]adenosine to blood incubating at 37 degrees C. The initial adenosine concentration was 10 nmol/ml blood. Aliquots of blood were removed at specific times following the addition of labelled adenosine. The aliquots were later assayed for adenosine and its products by reverse-phase high pressure liquid chromatography. The half-life for adenosine in undiluted blood was less than 10 s; therefore, to accurately evaluate the effects of dipyridamole, blood was diluted 1 : 12 in isotonic saline. At this dilution, the half-life for adenosine was 1.3 min. Dipyridamole concentrations of 1 nmol/ml blood caused 90% inhibition of adenosine metabolism. Inhibition was virtually complete, except for plasma deamination, at concentrations greater than 10 nmol/ml blood. Since these inhibitory concentrations of dipyridamole are on the same order as those achieved therapeutically in man, these data indicate that dipyridamole at therapeutic concentrations causes significant inhibition of adenosine metabolism in whole blood.

Adenosine↗
PubMed1989

Regulation of lipid metabolism by dipyridamole and adenosine antagonists in rat adipocytes.

1. Acute effects of dipyridamole, an inhibitor of adenosine transport, direct activators of adenylate cyclase and thirteen adenosine antagonist analogs on fatty acid synthesis have been examined in terms of the control of [1-14C]acetate incorporation into labeled fatty acids in the presence of glucose. 2. This monosaccharide acts as a stimulator of lipogenesis by generating NADPH for the lipid synthesis. 3. The relationship between lipogenesis and lipolysis was compared with a variety of adenylate cyclase stimulators. 4. The data obtained reveals that dipyridamole potentiated the inhibitory or stimulatory effects of isoproterenol and forskolin on lipogenesis and on lipolysis, respectively. 5. In these cases the data show that it exists an inverse relationship between lipogenesis and lipolysis. 6. Dipyridamole and methylxanthine analogs only moderately affect the rate of lipolysis whereas its effects are more potent on lipogenesis and lend further support to the hypothesis that dipyridamole antagonize adenosine actions as well as methyl xanthines. 7. These results suggest that dipyridamole and adenosine antagonists alter lipogenesis independently of the lipolytic process and that it exists an inverse relationship between lipogenesis and lipolysis under some conditions whereas there are not under others.

Adenosine↗