Development and application of a simple microassay for adenosine in rat plasma

Area of Science:

• Physiology
• Biochemistry
• Analytical Chemistry

Background:

• Adenosine is a key physiological modulator impacting vascular tone, sympathetic neurotransmission, and renal function.
• Understanding adenosine's role requires precise measurement in biological samples.
• Existing methods may necessitate larger sample volumes, potentially causing hemodynamic instability.

Purpose of the Study:

• To develop and validate a sensitive microassay for quantifying adenosine in rat plasma.
• To investigate the physiological role of adenosine, particularly in the context of renovascular hypertension.
• To establish baseline plasma adenosine levels in rats and assess changes under hypertensive conditions.

Main Methods:

• Development of a microassay utilizing reverse-phase Sep-Pak extraction and microbore high-performance liquid chromatography.
• Assay validation through linearity studies, infusion experiments, and adenosine deaminase incubation.
• Measurement of plasma adenosine levels in control and Goldblatt hypertensive rats.

Main Results:

• The microassay demonstrated high sensitivity and accuracy for adenosine quantitation in small plasma volumes (75 microliters).
• Mean arterial plasma adenosine level in anesthetized rats was determined to be 119 +/- 28 ng/ml.
• Renal venous plasma adenosine levels were found to be sixfold higher in two-kidney, one clip hypertensive rats compared to controls.

Conclusions:

• The developed microassay is a valuable tool for studying adenosine's physiological roles without inducing hemodynamic perturbations.
• Elevated renal venous adenosine in hypertensive rats supports its involvement in regulating renin release.
• Endogenous adenosine likely plays a significant role as a regulator of renin release in renovascular hypertension.