The factors affecting plasma catecholamines concentration in rats and man

: Rat and human plasma catecholamines were measured simultaneously by HPLC-THI, HPLC-ECD and REA, and the three methods were compared. An attempt was also made to determine the factors affecting the estimated value of plasma catecholamine concentration. Our study showed that: Sensitivity and reproducibility to norepinephrine and epinephrine were identical in all three methods. One advantage of the REA method is that comparatively smaller sample volumes are required to produce similar results. Plasma dopamine concentration in peripheral blood samples was determined by the HPLC-ECD rather than the HPLC-THI method. Withdrawal of 5 ml of blood produced a significant increase in norepinephrine, epinephrine and dopamine in rat plasma. The catecholamine concentration in these cases was determined by the REA method. Plasma norepinephrine concentration did not increase with age in Wistar Kyoto rats. However, plasma norepinephrine concentration increased significantly with age in stroke-prone spontaneously hypertensive rats (SHRSP). Plasma norepinephrine concentration in male SHRSP was greater than that in female SHRSP. SHRSP-plasma norepinephrine concentrations rose in parallel to increases in blood pressure. The plasma norepinephrine concentration in SHRSP with cerebral hemorrhage rose significantly as compared with the plasma norepinephrine levels in SHRSP without cerebral bleeding. Because each method of determination of plasma catecholamine concentration has both merits and demerits, selection should be determined by sample size and amount of catecholamines in the plasma samples. Factors affecting the estimated value of plasma catecholamine concentration should be taken into consideration.