Nitric oxide, L-NAME and moxonidine

Written by on November 28, 2005 in research with 0 Comments

The full article is available online, which is great, because this paper looks interesting but requires expertise to understand its significance.

Central blockade of nitric oxide synthesis reduces moxonidine-induced hypotension

British Journal of Pharmacology (2004) 142,

Thiago Santos Moreira, Ana Carolina Thomaz Takakura, José V Menani, Monica Akemi Sato and Eduardo Colombari.

Department of Physiology, Universidade Federal de Sao Paulo – Escola Paulista de Medicina, 04023-060, Sao Paulo, SP, Brazil.

  1. Nitric oxide (NO) and 2-adrenoceptor and imidazoline agonists such as moxonidine may act centrally to inhibit sympathetic activity and decrease arterial pressure.
  2. In the present study, we investigated the effects of pretreatment with L-NAME (NO synthesis inhibitor), injected into the 4th ventricle (4th V) or intravenously (i.v.), on the hypotension, bradycardia and vasodilatation induced by moxonidine injected into the 4th V in normotensive rats.
  3. Male Wistar rats with a stainless steel cannula implanted into the 4th V and anaesthetized with urethane were used. Blood flows were recorded by use of miniature pulsed Doppler flow probes implanted around the renal, superior mesenteric and low abdominal aorta.
  4. Moxonidine (20 nmol), injected into the 4th V, reduced the mean arterial pressure (-423 mmHg), heart rate (-227 bpm) and renal (-6215%), mesenteric (-418%) and hindquarter (-508%) vascular resistances.
  5. Pretreatment with L-NAME (10 nmol into the 4th V) almost abolished central moxonidine-induced hypotension (-103 mmHg) and renal (-104%), mesenteric (-114%) and hindquarter (-136%) vascular resistance reduction, but did not affect the bradycardia (-188 bpm).
  6. The results indicate that central NO mechanisms are involved in the vasodilatation and hypotension, but not in the bradycardia, induced by central moxonidine in normotensive rats.

Keywords: 2-Adrenoceptors, imidazoline receptors, hypertension, nitric oxide, blood flow, vascular resistance, blood pressure

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About the Author: David Pascoe started the Rosacea Support Group in October 1998. .

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