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Modulation Of The Baroreflex Depressant Effect Of Chronic Nicotine In Female Rats By Nitric Oxide Synthase And Heme Oxygenase
Author(s) -
ElMas Mahmoud M,
ElGowelli Hanan M,
Fouda Mohamed A,
ElGowilly Sahar M
Publication year - 2013
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.27.1_supplement.654.5
Subject(s) - nicotine , chemistry , heme oxygenase , nitric oxide synthase , chronotropic , pharmacology , nitric oxide , endocrinology , medicine , heme , blood pressure , biochemistry , heart rate , enzyme , organic chemistry
Nicotine impairs reflex chronotropic activity in female rats. Here, we sought evidence to implicate nitric oxide synthase (NOS) and/or heme oxygenase (HO) in the nicotine effect. Baroreflex curves relating chronotropic responses to reciprocal changes in blood pressure were generated by the vasoactive method (phenylephrine and nitroprusside) in nicotine‐treated female rats in absence and presence of NOS/HO pharmacological modulators. Slopes of the curves served as a measure of baroreflex sensitivity (BRS). Nicotine (2 mg/kg/day for 14 days) reduced BRS compared with saline‐treated rats. Findings that favor the involvement of NOS inhibition in the nicotine attenuation of BRS were (i) NOS inhibition (L‐NAME) reduced BRS in saline‐ but not in nicotine‐treated rats, and (ii) L‐arginine, NO donor, reversed the BRS inhibitory effect of nicotine. HO inhibition (protoporphyrin IX, ZnPP) had no effect on BRS in nicotine‐ or saline‐treated rats; it also failed to reverse the beneficial effect of L‐arginine on nicotine‐BRS interaction. Hemin (HO inducer) but not CORM‐2 (carbon monoxide releasing molecule) abolished the BRS attenuating effect of nicotine. Thus, the inhibition of NOS, but not HO, is causally related to nicotine‐evoked BRS depression. The latter can also be alleviated after HO induction. This project was supported financially by the Science and Technology Development Fund (STDF), Egypt, Grant No. 502.