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Simple validation for the hepatic venous cannula implanted chronically in conscious rats
1Department of Biochemistry, Chang Gung Medical College, Tao-yuan, Taiwan, Republic of China.
Journal of Applied Physiology (Bethesda, Md. : 1985)
|July 1, 1991
Summary
This study introduces a method to detect contamination in blood samples from rat hepatic venous cannulas using tritiated water washout patterns. Valid cannulas show specific tritium washout, enabling accurate hepatic blood flow measurements.
Area of Science:
- Physiology
- Pharmacology
- Surgical Techniques
Background:
- Accurate measurement of hepatic blood flow (HBF) is crucial in physiological and pharmacological research.
- Contamination of blood samples from hepatic venous cannulas with systemic circulation can lead to inaccurate HBF determinations.
- A reliable method is needed to validate the placement and integrity of hepatic venous cannulas.
Purpose of the Study:
- To describe and validate a method for detecting vena caval contamination in blood samples obtained via hepatic venous cannulas in conscious rats.
- To establish criteria for differentiating valid from invalid hepatic venous cannula placements based on tracer washout patterns.
- To determine hepatic blood flow using validated cannulas.
Main Methods:
- Bolus injection of tritiated water into the inferior vena cava.
- Concurrent continuous blood sampling from the hepatic venous cannula.
- Analysis of tritium washout patterns in sampled blood segments to detect systemic contamination.
- Determination of hepatic blood flow (HBF) using sulfbromophthalein (BSP) extraction in rats with validated and invalidated cannulas.
Main Results:
- A distinct tritium washout pattern was established for valid hepatic venous cannulas, falling within a specific range (1,400 to 1,930 cpm/sample).
- Invalid cannula placements, adjacent to the injection site, showed tritium washout patterns exceeding the established valid range.
- Hepatic blood flow (HBF) in rats with valid cannulas was determined to be 2.58 +/- 0.15 ml/min/g wet wt in conscious state and 2.76 +/- 0.26 ml/min/g wet wt in ketamine-anesthetized state.
Conclusions:
- The described method effectively detects vena caval contamination in hepatic venous cannula samples.
- This technique allows for the validation of cannula placement, ensuring the accuracy of subsequent hepatic blood flow measurements.
- Validated hepatic venous cannulation is essential for reliable physiological studies in rats.