The effects of mild hypothermia on coagulation tests and haemodynamic variables in anaesthetized rabbits / Efectos de la hipotermia leve sobre las pruebas de coagulación y las variables hemodinámicas en conejos anestesiados

OBJECTIVE: Hypothermia has been associated with coagulation defects. The purpose of this experimental study was to investigate the effect of mild hypothermia on clinically used coagulation tests and on haemodynamic variables. METHODS: Νine New Zealand rabbits were subjected to mild core hypothermia by administration of general anaesthesia and exposure to room temperature of 22°C for 60 minutes. Blood samples were obtained at normothermia and mild hypothermia for measurement of prothrombin time, activated partial thromboplastin time, fibrinogen levels, platelet count and haemoglobin concentration. Hypothermic values were compared to the normothermic values. Additionally, the progressive temperature drop and haemodynamic changes (blood pressure, heart rate) were recorded. RESULTS: Core temperature decreased significantly over time changing from 39.4 ± 0.27 to 36.6 ± 0.28°C (p = 0.0001). Prothrombin time and activated partial thromboplastin time decreased at hypothermia, but the changes were not statistically significant (p = 0.203 and p = 0.109, respectively). Platelet count, fibrinogen levels and haemoglobin concentration decreased significantly (p = 0.0001, p = 0.03 and p = 0.027) but remained within normal limits. Mean arterial pressure and heart rate declined significantly over time (p = 0.0001 and p = 0.0001, respectively). CONCLUSION: The results of this study suggest that short term mild hypothermia may affect the coagulation mechanism to a clinically nonsignificant extent, while haemodynamic responses are significantly suppressed.

OBJETIVO: La hipotermia ha sido asociada con defectos de coagulación. El propósito de este estudio experimental fue investigar el efecto de la hipotermia leve sobre las pruebas de coagulación de uso clínico, así como sobre las variables hemodinámicas. MÉTODOS: Nueve conejos de Nueva Zelanda fueron sometidos a hipotermia central leve mediante la administración de anestesia general y exposición a una temperatura ambiente de 22°C durante 60 minutos. Se obtuvieron muestras de sangre en condiciones de normotermia e hipotermia leve para medir el tiempo de protrombina, el tiempo de tromboplastina parcial activada, los niveles de fibrinógeno, el conteo de plaquetas, y la concentración de hemoglobina. Se compararon los valores hipotérmicos con los valores normotérmicos. Además, se registraron la caída progresiva de la temperatura y los cambios hemodinámicos (presión sanguínea, frecuencia cardíaca). RESULTADOS: La temperatura corporal central disminuyó significativamente con el tiempo, cambiando de 39.4 ± 0.27 a 36.6 ± 0.28°C (p = 0.0001). El tiempo de protrombina y el tiempo de tromboplastina parcial activado disminuyeron en la hipotermia, pero los cambios no fueron estadísticamente significativos (p = 0.203 y p = 0.109, respectivamente). El conteo de plaquetas, los niveles de fibrinógeno y la concentración de la hemoglobina disminuyeron significativamente (p = 0.0001, p = 0.03 y p = 0.027) pero permanecieron dentro de los límites normales. La presión arterial promedio y la frecuencia cardíaca disminuyeron significativamente con el tiempo (p = 0.0001 y p = 0.0001, respectivamente). CONCLUSIÓN: Los resultados de este estudio sugieren que la hipotermia leve a corto plazo puede afectar el mecanismo de la coagulación hasta un punto clínicamente no significativo, mientras que respuestas hemodinámicas se suprimen significativamente.

Improvement of skin-graft survival after autologous transplantation of adipose-derived stem cells in rats.

BACKGROUND: Skin grafts are frequently used for a variety of indications in plastic and reconstructive surgery. Their necrosis is a common complication, while different therapies have been proposed. Currently, adipose-derived stem cells (ASCs) hold great promise for their angiogenic potential and role during tissue repair. In this study, autologous transplantation of ASCs was used in skin grafts in rats to determine if it increases angiogenesis, skin-graft survival and wound healing. METHODS: ASCs were isolated, cultured, labelled with fluorescent dye and injected under full-thickness skin grafts in 10 rats (group 1), while 10 others served as controls (group 2). Skin grafts were analysed after 1 week. Collagen's framework was assessed with Masson's trichrome stain and angiogenesis with von Willebrand factor (vWF) immunohistochemistry. In addition, immunohistochemical staining intensity of vascular endothelial growth factor (VEGF) and transforming growth factor b3 (TGFb3) was assessed in all grafts. RESULTS: Mean area of graft necrosis was significantly less in group 1 than in group 2 (6.12% vs. 32.62%, p<0.01). Statistically significant increase of microvessel density, collagen density, VEGF and TGFb3 expression was noted in group 1 compared with group 2 (all: p<0.01). CONCLUSIONS: These findings suggest that autologous ASCs transplantation increases full-thickness skin-graft survival and shows promise for use in skin-graft surgery. This might be both due to in situ differentiation of ASCs into endothelial cells and increased secretion by ASCs of growth factors, such as VEGF and TGFb3 that enhance angiogenesis and wound healing.

Decreased tibial bone strength in postmenopausal women with aseptic loosening of cemented femoral implants measured by peripheral quantitative computed tomography (pQCT).

Aseptic loosening after total hip arthroplasty is related to bone loss of the operated leg. The aim of the present study was to investigate the effect of aseptic loosening on volumetric bone mineral density (vBMD) and bone geometry in the operated leg, in postmenopausal women with a loosened cemented femoral implant using peripheral quantitative computed tomography (pQCT). We matched 12 postmenopausal women with aseptic loosening of cemented femoral implant, with 12 women without aseptic loosening (control group) according to age, BMI, and years from operation. All patients underwent pQCT of both tibias, DXA of the lumbar spine, and determination of biochemical markers of bone turnover. pQCT values in the control group as well as the nonoperated legs between groups had no significant difference. In the aseptic loosening group, there was significant reduction of cortical vBMD (cort vBMD) at 14% and 38% sites (cortical site), cortical thickness at 38% site, and of polar stress strength index (SSIp) at 14% site (transition zone) in the operated compared with the nonoperated leg. Similarly, there was significant reduction of cort vBMD at 14% and 38% sites and total vBMD and trabecular vBMD (trab vBMD) at the 14% site in the operated legs between the two groups. The aseptic loosening group had increased osteocalcin and serum collagen cross-linked N- and C-telopeptides (sNTX and sCTX) levels compared with controls. Aseptic loosening is associated with significant decrease of cortical and trabecular vBMD, and impairment of bone geometry and strength only in the operated leg. Increased bone turnover probably represents a local phenomenon, and is not associated with systemic skeletal disease.

The effects of mild hypothermia on coagulation tests and haemodynamic variables in anaesthetized rabbits.

OBJECTIVE: Hypothermia has been associated with coagulation defects. The purpose of this experimental study was to investigate the effect of mild hypothermia on clinically used coagulation tests and on haemodynamic variables. METHODS: Nine New Zealand rabbits were subjected to mild core hypothermia by administration of general anaesthesia and exposure to room temperature of 22 degrees C for 60 minutes. Blood samples were obtained at normothermia and mild hypothermia for measurement of prothrombin time, activated partial thromboplastin time, fibrinogen levels, platelet count and haemoglobin concentration. Hypothermic values were compared to the normothermic values. Additionally, the progressive temperature drop and haemodynamic changes (blood pressure, heart rate) were recorded. RESULTS: Core temperature decreased significantly over time changing from 39.4 +/- 0.27 to 36.6 +/- 0.28 degrees C (p = 0.0001). Prothrombin time and activated partial thromboplastin time increased [corrected] at hypothermia, but the changes were not statistically significant (p = 0.203 and p = 0.109, respectively). Platelet count, fibrinogen levels and haemoglobin concentration decreased significantly (p = 0.0001, p = 0.03 and p = 0.027) but remained within normal limits. Mean arterial pressure and heart rate declined significantly over time (p = 0.0001 and p = 0.0001, respectively). CONCLUSION: The results of this study suggest that short term mild hypothermia may affect the coagulation mechanism to a clinically nonsignificant extent, while haemodynamic responses are significantly suppressed.

Malignant pleural effusion and talc pleurodesis. Experimental model regarding early kinetics of talc particle dissemination in the chest after experimental talc pleurodesis.

PURPOSE: Talc remains a commonly used agent for pleurodesis malignant pleural effusion. Nevertheless, it is associated with a 3-9% incidence of pulmonary reactions ranging from simple pneumonitis to acute respiratory distress syndrome (ARDS). The underlying lung pathology and the size and rate of talc particle dissemination have been implicated as the cause of these complications. There seems to be an acknowledged lack of evidence regarding detailed very early intrathoracic talc particle migration. MATERIALS AND METHODS: Thirty white male New Zealand rabbits underwent experimental pleurodesis and were randomly assigned to 3 (A, B, C) study groups (10 in each group). Rabbits were sacrificed 6, 12 and 18 h after talc administration. Samples from both lungs, mediastinum and parietal pleura were obtained. The number of talc crystals (m) deposited was counted and averaged along all slices of the various tissue samples. RESULTS: A high degree of early talc deposition and subsequent epithelial injury in all examined tissues was observed. Diffuse talc deposition occurred in both lungs, but in a different manner. On the side of talc administration, talc particles were deposited in a time-dependent fashion. On the contralateral side, talc was rapidly deposited during the first hours after the procedure, then the rate of deposition decreased, and increased again between 12 and 18 h after the procedure. CONCLUSION: Large-sized talc particles are deposited on both lungs very early after pleurodesis. At the same time inflammatory pulmonary changes appear bilaterally. Despite contradicting data in the literature, these findings should always be kept in mind when performing this procedure in high risk patients.

Efficacy of teicoplanin, administered in two different regimens, in the treatment of experimental endocarditis due to Enterococcus faecalis.

Using a rabbit model of endocarditis, we studied the efficacy of teicoplanin against a strain of Enterococcus faecalis resistant to ampicillin. Rabbits were randomly assigned to receive no antibiotics, teicoplanin 12 or 18 mg/kg of body weight every 12h, for 9 days. The effect of treatment on bacterial counts of vegetations and survival of the animals was evaluated at the end of treatment and 10 days thereafter. The two treatment regimens of teicoplanin produced peak serum levels 18.51+/-1.84 and 34.66+/-4.19 microg/ml, and trough levels above 10 x MIC of teicoplanin for the infecting organism. Both regimens resulted in significant bacterial reduction in the vegetations as compared to the control group (p<0.001). The drug prevented relapse of the infection 10 days after discontinuation of treatment. By increasing the teicoplanin dosage no additional therapeutic benefit was observed in terms of bacterial killing, sterilization of the vegetations, and survival of the animals, although the higher doses gave numerically superior results. These findings may have meaning for the optimum use of teicoplanin in the treatment of enterococcal endocarditis.

Diabetes may increase risk for oral cancer through the insulin receptor substrate-1 and focal adhesion kinase pathway.

In light of recent epidemiological studies that associate diabetes mellitus with increased risk for oral cancer, we investigated in diabetic (type I) and normal rats with induced oral squamous cell carcinoma whether the molecular basis for that putative association involves insulin receptor substrate-1 (IRS-1) and focal adhesion kinase (FAK). Fourteen diabetic and 12 normal rats developed cancer after 4-nitroquinoline-N-oxide treatment, while six diabetic and six normal animals were used as controls. Oral sections were studied using monoclonal antibodies against IRS-1 and FAK proteins. Expression of IRS-1 was significantly higher in diabetic than normal rats, but it decreased in diabetic animals with tumor, especially in more advanced stages. FAK expression was significantly higher in rats with cancer in comparison to the ones without it, regardless the diabetes status. These data suggest that the IRS-1/FAK pathway is altered by diabetes resulting in reduced cell adhesion and possibly increasing risk for oral cancer.

Cell proliferation and apoptosis culminate in early stages of oral oncogenesis.

Markers of cell proliferation (Ki-67 antigen) and apoptosis (Bax, Bcl-2) were studied in an experimental system of induced oral carcinogenesis in Syrian golden hamsters. Thirty-seven animals were divided into one control group and three experimental groups, which were treated with a carcinogen and sacrificed at 10, 14 and 19 weeks after treatment. The histological status of the lesions in the three experimental groups corresponded well with tumour advancement (from oral mucosal dysplasia to moderately differentiated squamous cell carcinoma). Tumour sections were studied using monoclonal antibodies against Bax, Bcl-2 and Ki-67 proteins. Pro-apoptotic Bax expression maintained high levels during all stages of oral carcinogenesis. Anti-apoptotic Bcl-2 expression decreased significantly in dysplastic and early invasion lesions and consequently increased almost to normal tissue level in consequent stages. Finally, Ki-67 expression increased sharply in initial stages of oral carcinogenesis, but significantly decreased in later stages.

Rapid alterations of serum oxidant and antioxidant status with the intravenous administration of n-6 polyunsaturated fatty acids.

In an attempt to achieve the safe intravenous administration of two n-6 polyunsaturated fatty acids (PUFAs), gamma-linolenic acid (GLA) and arachidonic acid (AA), and to study the subsequent changes on the total oxidant and antioxidant status, various steadily increasing doses of each acid were injected intravenously at different infusion times in 28 male rabbits. Blood samples were collected at 15-min time intervals by the hepatic veins and from the carotid artery; oxidant status was determined by the thiobarbiturate assay and total antioxidant status (TAS) was assessed by a colorimetric assay. Both n-6 PUFAs were administered with safety at a dose of 25 mg/kg within 10 min accompanied by an increase of malonodialdehyde concentrations in the hepatic veins and in the carotid artery 30-45 min, respectively, after the end of the infusion of GLA and/or AA. Similar changes did not occur in red cell membranes after the infusion of AA. TAS presented reciprocal changes to malonodialdehyde production; the main consumption of TAS was observed in all samples 30-60 min after the end of the infusion of n-6 PUFAs. The above-mentioned rapid alterations occurring in both serum oxidant and antioxidant status after GLA might have a future clinical therapeutic significance in conditions like cancer and disseminated infectious diseases.

Evidence of less severe aortic valve destruction after treatment of experimental staphylococcal endocarditis with vancomycin and dexamethasone.

The beneficial effects of therapy combining an antibiotic and dexamethasone have been reported in human studies on meningitis and in experimental studies on septic arthritis, nephritis, and endophthalmitis. Since most patients with staphylococcal endocarditis need a combination of medical and surgical treatment, the purpose of this study was to determine whether the addition of dexamethasone to vancomycin has any beneficial effect regarding the degree of valve tissue damage or the course of experimental aortic valve endocarditis caused by a methicillin-resistant strain of Staphylococcus aureus. Rabbits with catheter-induced aortic valve vegetations were randomly assigned to a control group and to groups receiving dexamethasone (0.5 mg/kg of body weight, intravenously [i.v.], twice a day [b.i.d]), vancomycin (30 mg/kg, i.v., b.i.d), or dexamethasone plus vancomycin, for a total of 10 doses (two doses per day for 5 days). The severity of valve tissue damage was significantly less in groups receiving vancomycin plus dexamethasone compared with that of the group receiving vancomycin alone (P < 0.001). The severity of tissue damage was inversely correlated with the mean polymorphonuclear leukocyte number in valve tissue. No statistically significant differences were observed between the vancomycin-treated group and the vancomycin-plus-dexamethasone-treated group in survival, blood culture sterilization rate, or reduction of the microbial burden (in CFU per gram) in valvular tissue. In conclusion, treatment with a combination of vancomycin and dexamethasone for 5 days reduces the severity of valve tissue damage in experimental staphylococcal aortic valve endocarditis. These findings could have significant implications in the treatment of staphylococcal endocarditis and deserve further confirmation in clinical trials.

Single-oral-dose azithromycin prophylaxis against experimental streptococcal or staphylococcal aortic valve endocarditis.

Azithromycin and ampicillin protected 94 and 72% of animals challenged with Streptococcus oralis, respectively (P = 0.177), while azithromycin and vancomycin protected 59 and 94% of the methicillin-resistant Staphylococcus aureus (MRSA)-challenged animals, respectively (P = 0.018). Azithromycin is effective in preventing experimental streptococcal endocarditis, but against MRSA it is less effective than vancomycin.

Antioxidant agent nimesulid and beta-blocker metoprolol do not exert protective effects against rat mitochondrial DNA alterations in adriamycin-induced cardiotoxicity.

Possible protective effects of two therapeutical agents (nimesulid and metoprolol) in adriamycin-induced cardiotoxicity were examined in rat cardiomyocytes at the mitochondrial DNA (mt DNA) level. Analysis by PCR revealed the presence of multiple deletions in a large region of the long arc of mt DNA which codes for several important genes involved in oxidative phosphorylation, in all animals under drug administration. No differences were found in the frequency of defective mt DNA between the animals that received only adriamycin (83%, 10/12), nimesulid and adriamycin (92%, 13/14), or metoprolol and adriamycin (80, 12/15) (p = 0.004).

Successful single-dose teicoplanin prophylaxis against experimental streptococcal, enterococcal, and staphylococcal aortic valve endocarditis.

Teicoplanin is a glycopeptide antibiotic that is administered both intramuscularly and intravenously. It has a prolonged half-life and a less toxic profile in comparison to those of vancomycin. The efficacy of a single dose of teicoplanin (18 mg/kg of body weight given intramuscularly) for the prevention of endocarditis due to Streptococcus oralis, Enterococcus faecium, and methicillin-resistant Staphylococcus aureus (MRSA) was evaluated after applying the rabbit model. Vancomycin at a single dose of 30 mg/kg given intravenously was used as the comparative agent for the prevention of endocarditis due to MRSA and E. faecium, while ampicillin at a single dose of 40 mg/kg given intravenously was used as the comparative agent for the prevention of endocarditis due to S. oralis. Rabbits in the teicoplanin group were infected at 1 h postdosing with approximately 10(7) CFU of each strain. Rabbits in the other groups were infected at 0.5 h postdosing with approximately 10(7) CFU of S. oralis (ampicillin group) or E. faecium and MRSA (vancomycin group). All rabbits were sacrificed 5 days later. Teicoplanin and vancomycin protected the animals challenged with E. faecium by 87.5 and 50%, respectively, and protected the animals challenged with MRSA by 100 and 92%, respectively. Teicoplanin and ampicillin protected the animals challenged with S. oralis by 100 and 77%, respectively. Prevention of endocarditis by teicoplanin was likely to be due to a prolonged inhibition of bacterial growth by the sustained supra-MICs. It is concluded that teicoplanin is very effective in preventing experimental streptococcal, enterococcal, and staphylococcal endocarditis and may be an attractive alternative antibiotic in patients allergic to beta-lactams, especially in the outpatient setting.

Ciprofloxacin and imipenem alone or in combination in experimental aortic valve endocarditis due to a ciprofloxacin borderline susceptible strain of Pseudomonas aeruginosa.

The in vivo efficacies of ciprofloxacin, imipenem and their combination were studied in the rabbit left-sided endocarditis model by using a seroresistant strain of Pseudomonas aeruginosa with borderline susceptibilities to ciprofloxacin (MIC/MBC 1 2 and 2 8 mug/ml to ciprofloxacin and imipenem, respectively). Both antimicrobials expressed synergy in vitro at the MBC level. Ciprofloxacin was given intramuscularly, 20 mg/kg of body weight q 8 h and imipenem at the same regimen intravenously for 9 days. When compared to the controls no significant differences were observed among the applied regimens regarding (1) blood culture sterilization, (2) percent of sterile vegetation, and (3) mean bacterial titers in vegetations. No strain isolated from vegetations at the end of therapy had developed resistance to either ciprofloxacin or imipenem. It is concluded that further studies are required after appropriate increase of ciprofloxacin dosage and more frequent administration and/or even higher doses of imipenem.

Vancomycin or vancomycin plus netilmicin for methicillin- and gentamicin-resistant Staphylococcus aureus aortic valve experimental endocarditis.

Using a rabbit model of aortic valve endocarditis, we studied the efficacy of vancomycin alone or in combination with netilmicin and/or rifampin against a methicillin- and gentamicin-resistant strain of Staphylococcus aureus (MGRSA). Antibiotics were given for 6 to 12 days, as follows: vancomycin (15 mg/kg of body weight every 12 h [BID] intravenously), vancomycin plus netilmicin (2.5 mg/kg BID intramuscularly), vancomycin plus rifampin (10 mg/kg BID intramuscularly), and vancomycin plus netilmicin plus rifampin at the same routes, dosages, and schedules mentioned above. Netilmicin was given to two additional groups at a higher dosage (6 mg/kg every 24 h intramuscularly) alone or in combination with vancomycin (15 mg/kg BID intravenously) for 12 days. All regimens resulted in undetectable bacterial counts in a significant proportion of vegetations (except netilmicin alone) or reduced the bacterial counts in the vegetations compared with the counts in the untreated controls (P<0.01 to P<0.001). No resistance to rifampin or netilmicin developed during therapy. It is concluded that in the treatment of experimental aortic valve endocarditis caused by MGRSA (i) vancomycin as monotherapy is as efficacious as the triple combination, (ii) the addition of netilmicin (once daily or BID) to vancomycin does not improve the efficacy of the latter antibiotic, even in the presence of rifampin, and (iii) a 12-day course in more effective than a 6-day one, but not at a statistically significant level.

Efficacy of ceftazidime and aztreonam alone or in combination with amikacin in experimental left-sided Pseudomonas aeruginosa endocarditis.

The in vivo efficacies of ceftazidime, aztreonam, and the combinations of ceftazidime with amikacin and aztreonam with amikacin were studied in the rabbit left-sided endocarditis model by using two strains of Pseudomonas aeruginosa, one multisusceptible and one multiresistant, in a total of 156 animals. Antibiotics were given intramuscularly for 10 days, as follows: amikacin, 7 mg/kg of body weight every 8 h, and ceftazidime and aztreonam, 50 mg/kg every 8 h. All regimens except amikacin alone significantly reduced the number of CFU per gram of vegetation (P < or = 0.008), but only for the multisusceptible strain for which sterile vegetations were obtained in 20, 25, 21, 75, and 53% of the groups treated with amikacin, ceftazidime, aztreonam, and the combination groups ceftazidime-amikacin and aztreonam-amikacin, respectively (ceftazidime plus amikacin versus controls, P = 0.001). Regarding the decrease in the numbers of colonies in vegetations, (i) all regimens significantly reduced the number of CFU per gram of vegetation (P < 0.001), (ii) results with ceftazidime-amikacin compared with those with monotherapy were significantly different (P < or = 0.007), and (iii) results with aztreonam-amikacin, although better than those with monotherapy, were marginally not statistically significant. At 1 h postdose, mean amikacin, aztreonam, and ceftazidime levels in serum were 35 +/- 19.4, 89.6 +/- 8.16, and 92.61 +/- 11.52 micrograms/ml, respectively. It was concluded that the combination of ceftazidime, and possibly aztreonam, with amikacin given at high doses and short intervals could have a place in the therapy of patients with left-sided endocarditis caused by P. aeruginosa.

The influence of hemodilution on left ventricular function.

In nine anesthetized mongrel dogs anemia was produced by exchanging blood with plasma substitute thus reducing hemoglobin gradually in three steps. Aortic, atrial and ventricular blood pressures, cardiac output, electrocardiogram, phonocardiogram and the first derivative of the left ventricular pressure were continuously monitored. Blood samples were taken to determine hemoglobin, blood gases and whole blood viscosity. Progressive hemodilution resulted in a significant increase in cardiac output and left ventricular stroke work, while total peripheral resistance, oxygen content and whole blood viscosity decreased significantly. There were no significant changes in cardiac pressures, myocardial contractility, diastolic pressure time index and blood gases. The oxygen supply/demand ratio had gradually declined, while electrocardiogram showed no significant changes. These results suggest that moderate isovolemic hemodilution in animals with normal coronary vessels does not impair left ventricular function as this was manifested by the unchanged hemodynamic and electrocardiographic findings.

Pharmacokinetics of calcium dobesilate in beagle dogs after a single administration.

A pharmacokinetic study was carried out in beagle dogs after a single intravenous infusion of 100 mg/kg of calcium dobesilate, a dose claimed to produce a cardiac lymphagogue effect. This effect on cardiac lymphatics is known to contribute to the reduction of myocardial infarct size after coronary artery occlusion. At the end of the intravenous infusion, which lasted about 30 minutes, the plasma level was 263 +/- 68 micrograms/ml, falling to 56 +/- 23 micrograms/ml by the third hour. This high plasma level of calcium dobesilate between the end of the infusion and the 3rd hour might explain the pharmacological effect of the drug on the cardiac lymphatic system.

Pharmacokinetics of calcium dobesilate in beagle dogs after repeated administration.

Many pharmacological findings suggest that repeated intravenous administration of calcium dobesilate improves myocardial lymphatic drainage, accelerates removal of degradation products and other toxic substances by increasing the number of functioning lymphatics and thus limits infarct size after experimental coronary artery occlusion. The aim of the present study was to investigate the relationship between the blood levels of calcium dobesilate and the pharmacological effect described above using the same dosage schedule. During the first six hours after intravenous administrations, at one hour interval, of three doses each of 100 mg/kg of calcium dobesilate, the average plasma level ranged from 414 micrograms/ml to 95 micrograms/ml with a plateau between the second and fourth hour. During this period, which is the most crucial for the ischemic myocardium, the effect of calcium dobesilate attained its optimum as evidenced by a statistically significant increase in the number of lymphatics visualized by lymphangiography and the reduction of infarct size measured by planimetry, by weight or by tomography. The plasma levels before the 18th hour were still higher than 10 micrograms/ml but no measurable calcium dobesilate was detected in the plasma at the 20th hour which indicates total elimination of the drug from the blood and thus precluding any risk of accumulation. The present results confirm that the doses of calcium dobesilate used in the pharmacological studies correspond to an adequate blood level.