Blood sampling by chronic cannulation technique for reliable measurements of catecholamines and other hormones in plasma of conscious rats.

An optimalized technique for chronic venous and arterial cannulation of rodents that permits repeated blood collections in unstressed, freely moving animals is presented. The indwelling catheter can also be used for chronic and/or acute drug administration in rats or other small laboratory animals, as well as for the recording of blood pressure and heart rate. The attachment device of minimal size is easily fixed on the head of the animals, allowing the additional implantation of a chronic cannula for intracerebral injections. No residual effects on the resting levels of plasma catecholamines (CA) were present 24-hr after surgery and anesthesia for implanting the cannula. No variations of plasma CA concentrations were observed at the different times of day examined or as a consequence of withdrawal of subsequent blood samples. Training the animals to be handled prevented the increase in plasma prolactin levels produced by decapitation; training had no influence on the decapitation-induced rises in plasma CA concentrations.