[Effects of cold on myocardial mitochondria respiration of rats with hypothyroidism treated with triiodothyronine].
The present work studied the effect of cold on oxygen consumption (OC) and alpha-glycerophosphate dehydrogenase activity (alpha-GPD) in heart mitochondria of hypothyroid rats (hypo) treated with T3, T4 or T4 plus Iopanoic Acid (IOP). 200 g male Wistar rats were made hypothyroid by 131I administration. Animals were injected s.c., in divided doses, for 10 days, with one of the following substances: T3, 300 ng/100 g BW/day; T4, 2 micrograms/100 g BW/day or T4 plus IOP, 5 mg/100 g BW/day, for 72 h preceding the experiment. One half of each group was housed in a cold room at 4 degrees C and the other at 22 degrees C, for 25 h, and thereafter decapitated. Heart mitochondria were isolated by routine methods. The OC was measured polarographically using L-malate, L-glutamate and malonate as substrates. Intramitochondrial alpha-GPD activity was measured by a microcolorimetric assay. The results from 16 or 20 rats/group (4 or 5 pools of 4 hearts each) were: In the rats kept at 22 degrees C the OC (in ng at. oxyg./min/mg prot.; State 3) in the hypo+T4 group was 69 +/- 10; in the rats treated with T4+IOP, 75 +/- 11 and in the hypo+T3, 102 +/- 5. When the animals were exposed to 4 degrees C no change was observed in the hypo+T4 and hypo+T4IOP groups. On the other hand, OC was significantly lower in the T3-treated animals (p less than 0.001, versus their controls at 22 degrees C). This group of rats did not survive when exposed to cold.(ABSTRACT TRUNCATED AT 250 WORDS)
Cageao
L F
LF
Centro de Medicina Nuclear, Hospital de Clínicas José de San Martín, Buenos Aires, Argentina.
de Mignone
I R
IR
Ricci
C R
CR
de Brignone
C M
CM
Altschuler
L R
LR
Brignone
J A
JA
Zaninovich
A A
AA
D000222:Adaptation, Physiological; D000818:Animals; D001833:Body Temperature Regulation; D003080:Cold Temperature; D005993:Glycerolphosphate Dehydrogenase / Q000378:metabolism*; D007037:Hypothyroidism / Q000188:drug therapy / Q000503:physiopathology; D008297:Male; D008929:Mitochondria, Heart / Q000502:physiology*; D010101:Oxygen Consumption / Q000502:physiology*; D051381:Rats; D011919:Rats, Inbred Strains; D013963:Thyroid Hormones / Q000627:therapeutic use; D014284:Triiodothyronine / Q000008:administration & dosage
D013963:Thyroid Hormones; D014284:Triiodothyronine; D005993:Glycerolphosphate Dehydrogenase
Efectos del frío sobre la respiración mitocondrial del miocardio de ratas hipotiroideas tratadas con triiodotironina.