Determination of myocardial norepinephrine in freely moving rats using in vivo microdialysis sampling and liquid chromatography with dual-electrode amperometric detection

Abstract

Myocardial norepinephrine (NE) is considered a meaningful parameter for estimation of cardiac function. Long lasting changes in myocardial NE appear to be not only a consequence of pathologic processes in the myocardium, but may be a factor responsible for some diseases (e.g. increased propensity for arrhythmias or negative effect on left ventricular contractility in congestive heart failure). In this respect monitoring of myocardial NE is of great importance. A microdialysis sampling technique coupled with liquid chromatography with electrochemical detection (LCEC) was developed to measure the in vivo NE concentration in the myocardial interstitium of conscious, freely moving rats. LCEC using a dual-electrode amperometric detection in the series configuration provided detection limits for NE of 10 pg/ml in 20 μl microdialysis samples. Microdialysis probes of the linear design were implanted in the myocardial tissue in the periphery of the left descending coronary artery. The basal steady-state concentration of NE in myocardial dialysate of awake, freely moving rats was found to be 0.17 ± 0.026 ng/ml. Delivery through the microdialysis probe of the NE reuptake inhibitor desipramine (DMI) at a concentration of 0.1 mM increased NE release to 153 ± 13% of control. If the concentration of DMI in the perfusate was increased to 1.0 mM, NE release increased to only 166 ± 21% of control.

Determination of endogenous norepinephrine levels in different chambers of the rat heart by capillary electrophoresis coupled with amperometric detection

“…A related finding is the depletion of NE that occurs in all heart chambers following cardiac transplantation (Mohanty et al, 1986). In order to better understand SNS dysfunction in cardiovascular disease, it is important to have a reliable method for monitoring NE content, and its metabolites, both during disease development and in the chronic disease state (Berquist et al, 2002;Gilinsky et al, 2001;Makoto, 2006;Nikolajsen and Hansen, 2001;Peaston and Weinkove, 2004).…”

“…HPLC with electrochemical detection is the most commonly used method for quantitative determination of biogenic amines and metabolites in tissue, plasma and urine (Cheng and Kuo, 1995;Chi et al, 1999;Davis et al, 1981;Gilinsky et al, 2001;Machida et al, 2006;Patel et al, 2005;Sabbioni et al, 2004;Sastre et al, 2004;Unceta et al, 2001). Another informative, but less used technique, for bioanalyte monitoring in tissue is capillary electrophoresis (CE) (Dillon and Sears, 1998;Markuszewski et al, 2003;Paxon et al, 2005;Qurishi et al, 2002;Shou et al, 2004).…”

Current separation and detection methods in microdialysis the drive towards sensitivity and speed

“…Gilinsky et al [26] used LC with ECD to measure myocardial norepinephrine (NE) and reported detection limits of 10 pg/mL in 20 mL MD sample sizes. NE has been closely related to changes in cardiac functioning.…”

Analytical Considerations for Microdialysis Sampling

“…This technique has been employed extensively for pharmacokinetic and pharmacodynamic studies as well as for drug delivery. Microdialysis has been used to monitor drugs and other biologically important compounds in virtually every tissue and organ in the body, including liver [1,2] , heart [3,4] , skin [5,6] , blood [7,8] , placenta [9] , stomach [10,11] , ear [12] , and brain [13,14] .…”