Changes in the vascular bed of submandibular glands after chronic autonomic denervation

The effect of chronic sympathetic denervation (SCG) or parasympathetic decentralization (PSD) on the vascularization of the submaxillary gland (SM) of rat was studied in connection with morphological and functional changes. The resection of the superior cervical ganglion or the section of the chorda tympani was performed in adult male Wistar rats prior to the injection of Microfil MV Orange 3.25 cm3/kg. Once dissected, the glands were made transparent in increasing concentrations of methyl salicylate--alcohol. Three longitudinal sections were performed and the central one was projected in an automatic image analyzer (Kontron Zeiss), where vascular length and vascular volume were measured. Another group of animals was injected with Microfil after having received an injection of noradrenaline (10 g/kg) in SCG glands and methacholine in PSD glands. In SCG glands, vascular length underwent a 60% increase and the vascular volume increased from 0.26 +/- 0.15 cu mm/cu mm in controls to 0.54 +/- 0.15 cu mm/cu mm in SCG. The intravenous administration of noradrenaline prior to Microfil injection reverted the phenomenon. PSD caused a reduction of the vascular bed which resulted mainly in increased vascular volume. The administration of methacholine (10 g/kg) reverted the-response. It was concluded that SCG induced a loss of the existing vasoconstrictor tone, thus causing increase of vascular length and volume (passive vascular dilatation). Increased vascular volume after chronic PSD is compatible with vascular stasis and the absence of variations in vascular volume after the injection of methacholine would indicate that in the SM glands of rats there is no vascular dilatation tone.