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Published on: September 11, 2018
A fluctuation in adrenocepter- and muscarinic receptor-mediated blood pressure responses in acute hyperthyroid rats
Hideo Honda1, Takeshi Iwata, Takuya Mochizuki
1Department of Pharmacology, Tokyo University of Pharmacy and Life Science, 1432-1 Horinouchi, Hachioji, Japan. hhonda@ps.toyaku.ac.jp
Abstract:
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.
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