A newborn rat model for the study of cerebral hemodynamics by near-infrared spectroscopy and laser-Doppler flowmetry in the immature brain.

An animal model for the study of cerebrovascular physiology in the immature brain was developed. Twelve 3- to 5-day-old rat pups were maintained on spontaneous breathing under light anesthesia for either 1 or 2 h. Transcutaneous carbon dioxide tension and arterial oxygen saturation were monitored. Continuous infusion of doxapram limited respiratory acidosis. Cerebral blood flow (CBF) and volume (CBV) could be monitored by near-infrared spectroscopy (NIRS) and laser-Doppler flowmetry (LDF) in spite of some movement artifacts. CBV and CBF were 6.0 +/- 0.3 SE ml/100 g and 36.3 +/- 3.1 SE ml/100 g/min, respectively, and remained stable during the study. Cerebrovascular responses, as monitored by LDF and NIRS, to hypoxic and hypercapnic gas mixtures were consistent.