THE EFFECT OF BILATERAL REMOVAL OF THE SUBMANDIBULARY SALIVARY-GLANDSON THE ERYTHROPOIETIC RESPONSE OF MICE

The role of the submandibular salivary gland in erythropoiesis in the male mouse (MRC TO strain) was evaluated by subjecting mice without su bmandibular salivary glands (SX) and control (C) sham-operated mice to a variety of stimuli intended to stress the erythropoietic system. In SX mice, after removal of the submandibular glands at age 4 weeks and observation for 8 weeks, mean hematocrit was the same as in C mice, b ut mean body weight was less. Bilateral removal of the submandibular g lands at age 6 weeks neither affected the rate of fall and subsequent recovery of hematocrit which followed treatment with phenylhydrazine ( 80 mg/kg intraperitoneally [i.p.] 9 days after operation) nor altered the rate of increase in hematocrit or change in body weight which occu rred during hypobaric hypoxia (0.5 atm, >23 hours/day) for 23 days. Me an (SEM) estimates of serum immunoreactive erythropoietin after 17 hou rs' continuous hypobaric (0.5 atm) exposure were not significantly dif ferent between SX [186 (30) mU/mL, n=7] and C mice [232 (17) mU/mL, n= 7]. In mice given bilateral nephrectomies at age 6 weeks-2 weeks after SX or C surgery-and then both treated with phenylhydrazine (60 mg/kg i.p.) and exposed for 17 hours to hypobaric (0.5 atm) hypoxia, mean es timates of serum immunoreactive erythropoietin were 22.6 (10.6) mU/mL and 22.3 (5.4) mU/mL in SX (n=5) and C (n=5) mice. Results of the stud y do not support the premise that the submandibular salivary glands ei ther contribute to the erythropoietic response or are a source of extr arenal erythropoietin.