Role of cardiac eNOS expression during pregnancy in the coupling of myocardial oxygen consumption to cardiac work.
We assessed whether pregnancy results in enhanced nitric oxide (NO)-mediated control of myocardial oxygen consumption. Rats were studied before (C), at 1 wk (1w) or 2 wk (2w) of pregnancy, and at 4 days after giving birth (-4d). Left ventricular endothelial NO synthase (eNOS) protein expression was determined by immunoblotting. Oxygen consumption of left ventricular tissue samples was measured in vitro in response to increasing doses of bradykinin with or without addition of the NOS inhibitor N(G)-nitro-L-arginine methyl ester (L-NAME). Echocardiography indicated an increased cardiac output during pregnancy. Myocardial eNOS protein expression significantly increased by 46 +/- 9 and 39 +/- 8% at 1w and 2w, respectively, and returned to control levels at -4d. Bradykinin (10(-4) M) decreased cardiac oxygen consumption in a NO-dependent manner by 17 +/- 2% at C, by 21 +/- 2% at 1w, by 24 +/- 2% at 2w (P < 0.05 vs. C and -4d), and by 18 +/- 1% at -4d. Myocardial eNOS protein expression is transiently increased during pregnancy in rats, and this increase is associated with enhanced NO-dependent control of myocardial oxygen consumption at a time when cardiac output is increased.
New York Medical College, Department of Physiology, Valhalla, New York 10595, USA.
Axel
A
Linke
Wei
W
Li
Harer
H
Huang
Ziping
Z
Wang
Thomas H
TH
Hintze
D017311:Amlodipine / Q000494:pharmacology; D000806:Angiotensin-Converting Enzyme Inhibitors / Q000494:pharmacology; D000818:Animals; D000959:Antihypertensive Agents / Q000494:pharmacology; D001920:Bradykinin / Q000494:pharmacology; D002302:Cardiac Output / Q000502:physiology*; D004452:Echocardiography; D004656:Enalapril / Q000494:pharmacology; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005260:Female; D006321:Heart / Q000033:anatomy & histology / Q000502:physiology; D009206:Myocardium / Q000201:enzymology*; D019331:NG-Nitroarginine Methyl Ester / Q000494:pharmacology; D009569:Nitric Oxide / Q000378:metabolism; D020030:Nitric Oxide Donors / Q000494:pharmacology; D019001:Nitric Oxide Synthase / Q000378:metabolism*; D052250:Nitric Oxide Synthase Type III; D010101:Oxygen Consumption / Q000187:drug effects / Q000502:physiology*; D010396:Penicillamine / Q000031:analogs & derivatives* / Q000494:pharmacology; D011247:Pregnancy; D011270:Pregnancy, Animal / Q000502:physiology*; D051381:Rats; D017207:Rats, Sprague-Dawley
D000806:Angiotensin-Converting Enzyme Inhibitors; D000959:Antihypertensive Agents; D004791:Enzyme Inhibitors; D020030:Nitric Oxide Donors; C110881:S-nitro-N-acetylpenicillamine; D017311:Amlodipine; D009569:Nitric Oxide; D004656:Enalapril; D019001:Nitric Oxide Synthase; D052250:Nitric Oxide Synthase Type III; C496316:Nos3 protein, rat; D010396:Penicillamine; D001920:Bradykinin; D019331:NG-Nitroarginine Methyl Ester