Prenatal exposure to carbon monoxide and vascular responsiveness of rat resistance vessels

The aim of the present study was to investigate the influence of prenatal exposure to carbon monoxide (CO) on vascular reactivity of rat resistance vessels, in different stages of neurogenesis. Both prenatally CO-exposed and control male Wistar pups (5-7, 9-11, 14-16, 20-22 days) were tested vs respective 60 day adult rats. The results showed that: (i) at 5-7 days of age, TTX caused a more marked inhibition of perivascular nerve stimulation (PNS)-evoked vasoconstriction in CO-exposed animals with respect to controls; (ii) the NO-related relaxant effect by ACh in CO-exposed group appeared earlier (5-7 days) than in control group (9-11 days); (iii) the contractile response evoked by ACh on resting tone disappeared earlier (after 14-16 days) than in control group (after 20-22 days). These observations suggested that CO-exposure might induce changes in nerve electrophysiological properties and might cause a precocious maturation of the NO-related enzymatic mechanism implicated in ACh-relaxation.