A fluctuation in adrenocepter- and muscarinic receptor-mediated blood pressure responses in acute hyperthyroid rats.
Hyperthyroidism was induced by daily subcutaneous injections of L-thyroxine (T(4), 0.5 mg/kg/day) for 3 days, 1 week, or 2 weeks to study whether there is a fluctuation in adrenoceptor- and muscarinic receptor-mediated blood pressure responses at a hyperthyroid stage. T(4) treatment for 3 days or 1 week significantly suppressed the pressor response induced by norepinephrine (NE). The depressor responses induced by isoprenaline or acetylcholine (ACh) were increased by T(4) treatment for only 3 days. The pressor response induced by N(G)-nitro-L-arginine (L-NA) was increased by T(4) treatment for only 3 days. Results suggest that adrenoceptor- and muscarinic receptor-mediated blood pressure responses fluctuate in hyperthyroidism caused by T(4) in rats, that the basal nitric oxide (NO) production and/or release are increased in hyperthyroid rats at an early stage of the disease.
Honda
Hideo
H
Department of Pharmacology, Tokyo University of Pharmacy and Life Science, 1432-1 Horinouchi, Hachioji, Japan. hhonda@ps.toyaku.ac.jp
Iwata
Takeshi
T
Mochizuki
Takuya
T
Kogo
Hiroshi
H
D000208:Acute Disease; D000818:Animals; D001794:Blood Pressure / Q000187:drug effects / Q000502:physiology*; D006980:Hyperthyroidism / Q000139:chemically induced / Q000503:physiopathology*; D008297:Male; D009569:Nitric Oxide / Q000502:physiology; D051381:Rats; D017208:Rats, Wistar; D011941:Receptors, Adrenergic / Q000502:physiology*; D011976:Receptors, Muscarinic / Q000502:physiology*; D013974:Thyroxine / Q000633:toxicity
D011941:Receptors, Adrenergic; D011976:Receptors, Muscarinic; D009569:Nitric Oxide; D013974:Thyroxine