Effects of thyroid hormone on. beta. -adrenergic responsiveness of aging cardiovascular systems
The authors have compared the effects of ..beta..-adrenergic stimulation on the heart and peripheral vasculature of young (2-mo-old) and older (12-mo-old) rats both in the presence and absence of triiodothyronine (T/sub 3/)-induced hyperthyroidism. The hemodynamic consequences of T/sub 3/ treatment were less prominent in the aged hyperthyroid rats compared with young hyperthyroid rats (both in intact and pithed rats). There was a decrease in sensitivity of chronotropic responsiveness to isoproterenol in older pithed rats, which was apparently reversed by T/sub 3/ treatment. The number and affinity of myocardial ..beta..-adrenergic receptor sites measured by (/sup 125/I)cyanopindolol were not significantly different in young and older control rats; also, ..beta..-receptor density increased to a similar extent in both young and older T/sub 3/-treated rats. The ability of isoproterenol to relax mesenteric arterial rings, markedly blunted in older rats, was partially restored by T/sub 3/ treatment without their being any change in isoproterenol-mediated relaxation in the arterial preparation from young rats. The number and affinity of the ..beta..-adrenergic receptors measured in the mesenteric arteries was unaffected by either aging or T/sub 3/ treatment. The data suggest that effects of thyroid hormone and age-related alterations of cardiovascular responsiveness to ..beta..-adrenergic stimulation are interrelated in a complex fashion with a net result that the hyperkinetic cardiovascular manifestations in hyperthyroidism are attenuated in the older animals.
- Research Organization:
- Yamanashi Medical College, Japan
- OSTI ID:
- 5993972
- Journal Information:
- Am. J. Physiol.; (United States), Vol. 252:3
- Country of Publication:
- United States
- Language:
- English
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59 BASIC BIOLOGICAL SCIENCES
CARDIOVASCULAR SYSTEM
PHYSIOLOGY
SYMPATHOMIMETICS
RADIORECEPTOR ASSAY
TRIIODOTHYRONINE
BIOLOGICAL EFFECTS
AGE DEPENDENCE
BLOOD VESSELS
HEART
HYPERTHYROIDISM
INDOLES
IODINE 125
RATS
RECEPTORS
ANIMALS
AROMATICS
AUTONOMIC NERVOUS SYSTEM AGENTS
AZAARENES
AZOLES
BETA DECAY RADIOISOTOPES
BODY
DAYS LIVING RADIOISOTOPES
DISEASES
DRUGS
ELECTRON CAPTURE RADIOISOTOPES
ENDOCRINE DISEASES
HETEROCYCLIC COMPOUNDS
HORMONES
INTERMEDIATE MASS NUCLEI
IODINE ISOTOPES
ISOTOPE APPLICATIONS
ISOTOPES
MAMMALS
MEMBRANE PROTEINS
NUCLEI
ODD-EVEN NUCLEI
ORGANIC COMPOUNDS
ORGANIC NITROGEN COMPOUNDS
ORGANS
PEPTIDE HORMONES
PROTEINS
PYRROLES
RADIOISOTOPES
RODENTS
THYROID HORMONES
TRACER TECHNIQUES
VERTEBRATES
550601* - Medicine- Unsealed Radionuclides in Diagnostics
551001 - Physiological Systems- Tracer Techniques