[Determination of polyphenols in tobacco by solid phase extraction and high performance liquid chromatography]

A high performance liquid chromatographic (HPLC) method for the determination of polyphenols in tobacco was studied. Polyphenols can be extracted from tobacco sample by refluxing with 80% (volume fraction) methanol, then subjected to degrease by solid phase extraction with Sep-Pak-C18 column. Chlorogenic acid, rutin, scopoletin, caffeic acid, scopolin and other polyphenols can be separated on a Nova-Pak-C18 column (3.9 mm i.d. x 150 mm) gradiently eluted with methanol and 0.05 mol.L-1 potassium dihydrogen phosphate buffer solution as mobile phase at a flow-rate of 0.5 mL.min-1. Polyphenols were determined at the maximum wavelength of each polyphenol, for chlorogenic acid 326.1 nm, rutin 354.8 nm, scopoletin 344.0 nm, caffeic acid 323.7 nm and scopolin 365.2 nm by photodiode array detector. The main polyphenols in tobacco can be identified with UV spectroscopy. The recoveries of tobacco polyphenols were 94%-105%, and the relative standard deviations were 1.28%-1.49%. This method can be applied to the determination of polyphenols in tobacco with satisfactory results.

A model of cyanotic heart disease: functional, pathological, and metabolic sequelae in the immature canine heart

To assess the etiology of depressed ventricular function in cyanotic congenital heart disease, an experimental model in immature puppies was devised in which the left atrial appendage is directly anastamosed to the distally banded pulmonary artery. The preparation results in significant cyanosis during a 3-month study period (PO2 = 91 +/- 4 vs 43 +/- 3, hematocrit = 33 +/- 3 vs 55 +/- 5). Compared to age- and weight-matched unoperated controls, cyanotic animals developed significant depression of biventricular ejection fraction (P less than 0.05), increased heart weight indexed for body weight (P less than 0.05), increased right ventricular weight (P less than 0.02), and increased right ventricular free wall thickness (P less than 0.05). There was no alteration in ventricular volumes. In addition, mean myocardial stores of high-energy phosphate compounds were unaltered. The model allows a reproducible level of hypoxemia to be produced in young animals, utilizes no prosthetic materials, and allows future experiments to be performed to ascertain the metabolic response of the cyanotic myocardium to exercise or surgically induced ischemia.

Chronic hypoxemia depresses global ventricular function and predisposes to the depletion of high-energy phosphates during cardioplegic arrest: implications for surgical repair of cyanotic congenital heart defects

Persistence of impaired ventricular function after repair of cyanotic congenital heart defects may be due to previous exposure to chronic hypoxemia or to perioperative ischemic injury. Clarification of this phenomenon was sought in a canine model of cyanotic cardiovascular disease (Group I), in which the left atrium was anastomosed proximal to the banded pulmonary artery. Animals that had pulmonary artery banding alone (Group II) or no prior surgical intervention (Group III) served as controls. All Group I animals became cyanotic during the study period (arterial oxygen tension, 38 +/- 4 mm Hg; hematocrit, 55 +/- 5%). Radionuclide-determined ejection fractions performed three months after operation showed significant depression of global biventricular function by 16 to 29% (p less than 0.05) compared with groups II and III. On cardiopulmonary bypass, all hearts were subjected to 4 degrees C potassium cardioplegic arrest and reperfusion with serial assays for myocardial adenosine triphosphate (ATP) and creatine phosphate (CP) levels. The ATP and CP stores in each ventricle were similar at all sampling intervals, and preischemic levels were comparable in cyanotic and control groups. However, ATP levels were significantly depressed 37 to 43% from preischemic levels (p less than 0.02) after arrest and reperfusion in cyanotic dogs, but they were preserved in Groups II and III. During ischemia, CP stores were depleted to 27% of preischemic values in Group I but only to 46 to 63% of preischemic levels in the control groups (p less than 0.05). These data indicate that chronic hypoxemia impairs global ventricular function and predisposes to the accelerated depletion of high-energy phosphates during cardioplegic arrest.(ABSTRACT TRUNCATED AT 250 WORDS)