L-Arginine Improves Diminished Cerebral CO2 Reactivity in Patients

C. Zimmermann, R.L. Haberl
2003 Stroke  
and Purpose-There is experimental evidence that L-arginine restores diminished CO 2 reactivity after mild traumatic brain injury in rats. This effect is believed to be mediated by L-arginine-derived nitric oxide, which is a permissive substrate for CO 2 reactivity. To clarify whether these findings can be transferred to the clinical situation and have beneficial effects in patients, we studied the effects of L-arginine on CO 2 reactivity of the cerebral vessels in patients with impaired
more » ... r reactivity (VMR) and compared them with patients with normal VMR. Methods-Twenty-two patients with cardiovascular risk factors and VMR Ͻ50% with no extracranial or intracranial stenoses were examined by bilateral transcranial Doppler sonography of the right and left middle cerebral arteries and compared with 20 age-and risk-matched patients with normal VMR (Ͼ50%). VMR was tested by 1-minute hyperventilation, followed by a 3-minute inhalation of 5% CO 2 . Examinations were performed before and after infusion of 30 g L-arginine over 30 minutes. The 22 patients with reduced VMR (Ͻ50%) were compared with 20 patients with normal VMR (Ͼ50%). Results-Initial mean VMR of the 42 patients was 50Ϯ12%. There was no difference between the right-and the left-side VMR. In the 22 patients with reduced VMR in the first examination (42Ϯ8%), VMR increased significantly after infusion of L-arginine (52Ϯ14%, Pϭ0.005). In contrast, values did not change after infusion of L-arginine in the 20 patients with normal VMR (59Ϯ8% before versus 59Ϯ13% after L-arginine). There was a negative correlation of initial CO 2 vasoreactivity and the percentage of VMR increase after infusion of L-arginine. Conclusions-Our data support the hypothesis that in humans L-arginine is able to improve impaired CO 2 reactivity of the cerebral vessels. This effect can be found in patients at cardiovascular risk with impaired VMR and might have therapeutic implications in the future. (Stroke. 2003;34:643-647.)
doi:10.1161/01.str.0000056526.35630.47 pmid:12624285 fatcat:erg53e7htzcj7etfsj443ckeei