Developmental status of sympathetic innervation in relation to calcium accumulation by submandibular gland following reserpine, surgical sympathectomy or cyclocytidine

Sympathectomy (Sx) of the submandibular gland was induced at various postnatal ages by ip administration of a single dose of reserpine or by unilateral excision of a superior cervical ganglion. If animals were 12 days old or less at the time of drug administration, Ca] of the submandibular gland was not measurably increased 24 hr later; if rats were 14 days of age or older, Ca] of the gland 24 hr after reserpine injection was nearly double that of untreated controls. Two days after surgical Sx, Ca] of the denervated submandibular gland was unchanged from that of the innervated member of a pair if animals were less than 14 days of age at the time of denervation; Ca] was twice that of glands of control rats if animals were older than 14 days of age when the denervation was performed. The anti-tumor agent, cyclocytidine (CC), given daily for 3 days in an ip dose of 500 mg/kg, also caused a two- to threefold increase in Ca] of the submandibular gland when rats were more than 12 days of age at the time of the initial injection of the drug, but in rats younger than this age, CC caused no change in the Ca] of the submandibular gland. Present data show that there are age-related differences in the ability of the submandibular gland to accumulate calcium following sympathetic denervation or treatment with a norepinephrine-releasing drug. These differences may be attributed either to incomplete development of calcium transport mechanisms, or incomplete development of the sympathetic innervation before 14 days of age.