Vagus-sparing gastric fundectomy in the rat: development of osteopenia, relationship to urinary phosphate and net acid excretion, serum gastrin and vitamin D

In man and experimental animals, partial and total gastrectomy and gastric vagotomies disturb extracellular mineral homeostasis. osteopenia being amon g the late outcomes; The sequence of events is complex and insufficiently u nderstood. We report on the long-term effects of gastric fundectomy (FX; FX -1, n = 11; sham-operated controls, n = 14) sparing gastric vagal fibers at the lesser curvature in the rat, a procedure eliminating gastric acid prod uction but preserving gastric reservoir function. After FX-1 there was a ma rked increase of gastrinemia [FX-1: 590 (SE 95); controls: 82 (5) pg-equiv/ ml; P < 0.0011, serum 1,25-dihpdroxyvitamin D [FX-1: 188 (17); controls: 86 (6) pg/ml; P < 0.001], phosphaturia [FX-I: 32 (2); controls 23 (2) mu mol/ h; P < 0,001] due to increased fractional phosphate clearance, elevated uri nary net acid [FX-1: 21 (2); controls. 16 (1) <mu>mol/h; P = 0.031, and low urinary pH. The urinary excretion of hydroxyproline was increased [FX-1: 1 37 (15); controls. 99 (8) mu mol/h; P = 0.01], and crosslinks were also hig h. These changes were associated with a significant decrease of bone ash ca lcium, magnesium, and phosphorus. Bone histomorphometry revealed signs of h igh bone turnover. No signs of hyperparathyroidism were detectable. Acute s timulation of serum gastrin by gastric acid abolishing omeprazole failed to provoke extra-osseous changes, as seen in the long-term after fundectomy. It was concluded that the described type of fundectomy disturbs gastrinemia , acid-base and phosphorus metabolism, thereby initiating osteopenia. This animal model may be suitable for research into post-gastrectomy bone diseas e.