MANAGEMENT OF TETANY IN HYPOCALCEMIC MODELS IN THE RAT

Abstract

Bone remodeling and calcemia decrease when levels of PTH ae low. This situation can be obtained by ablation of either thyroid and parathyroid glands (TPTX) or parathyroid glands (PX). Both surgeries produce calcemia lower than 7.5 mg/dl. After these surgeries, hypocalcemia and tetany make difficult the follow up of rats under treatments and surgeries. The objective of this work was the development of hypocalcemic models with controlled tetany. After PX, TPTX and ablation of one parathyroid gland (1/2PX), calcemia (before and, 5 and 20 days after surgery), tetany and survival were assessed. Results were expressed as mean±SEM and differences were considered significant when p <0.05. Experimental groups (n=8 each): G1:

PX, G2: PX+calcium gluconate (CaG) in the drinking water. After 5 days rats of G2 were subjected to general anesthesia and divided into G2a: without treatment, and G2b: with intramuscular CaG administration. G3: PX+ CaG in the drinking water+ water without CaG, G4: 1/2PX+CaG in the drinking water, G5: TPTX. Calcemia (mg/dl) before surgery was not different among groups. Calcemia after 5 days was lower in all groups when compared to the day of surgery (G1:4.8±0.7, G2:7.6±0.8, G2a:7.2±0.5, G2b:7.7±1.3, G3:5.9±0.8, G4:3.5±4.9, G5:7.6±0.3). Rats of G1 developed tetany, not present in the other groups. G2a and G2b had tetany after anesthesia. The intramuscular injection of CaG in G2b reversed tetany. Calcemia at day 5 were lower in G1 and G4 compared to the other groups. Conclusions: 1- PX and 1/2PX produced a more severe hypocalcemia than TPTX. 2- The administration of CaG in the drinking water prevented tetany, but not under anesthesia. 3- 1/2 PX is a model of transitory severe hypocalcemia. 4- The intramuscular administration of CaG reversed tetany.