Intense exercise causes decrease in expression of both endothelial NO synthase and tissue NOx level in hearts

Motoyuki Iemitsu, Takashi Miyauchi, Seiji Maeda, Koichi Yuki, Tsutomu Kobayashi, Yoshito Kumagai, Nobuhiro Shimojo, Iwao Yamaguchi, Mitsuo Matsuda

Research output: Contribution to journalArticlepeer-review

48 Citations (Scopus)

Abstract

Cardiac myocytes produce nitric oxide (NO). We studied the effects of intense exercise on the expression of NO synthase (NOS) and the tissue level of nitrite (NO2/-)/nitrate (NO3/-) (i.e., NOx), which are stable end products of NO in the heart. Rats ran on a treadmill for 45 min. Immediately after this exercise, the heart was quickly removed. Control rats remained at rest during the same 45-min period. The mRNA level of endothelial NOS (eNOS) in the heart was markedly lower in the exercised rats than in the control rats. Western blot analysis confirmed downregulation of eNOS protein in the heart after exercise. Tissue NOx level in the heart was significantly lower in the exercised rats than in the control rats. The present study revealed for the first time that production of NO in the heart is decreased by intense exercise. Because NO attenuates positive inotropic and chronotropic responses to β1-adrenergic stimulation in the heart, the decrease in cardiac production of NO by intense exercise may contribute to the acceleration of increase in myocardial contractility and heart rate during intense exercise.

Original languageEnglish
Pages (from-to)R951-R959
JournalAmerican Journal of Physiology - Regulatory Integrative and Comparative Physiology
Volume279
Issue number3 48-3
DOIs
Publication statusPublished - 2000
Externally publishedYes

Keywords

  • Chronotropic effect
  • Inotropic effect
  • Nitric oxide
  • Nitric oxide synthase
  • Treadmill running

ASJC Scopus subject areas

  • Physiology
  • Physiology (medical)

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