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Ann Thorac Surg. 2004 Jan;77(1):126-32.

Nitric oxide and prostacyclin in ultrasonic vasodilatation of the canine internal mammary artery.

Author information

1
Division of Cardiovascular Surgery, Mayo Clinic, Rochester, Minnesota 55905, USA.

Abstract

BACKGROUND:

Investigators recently demonstrated increased free blood flow from radial artery free grafts harvested using ultrasonic technology. We investigated the mechanism underlying this phenomenon.

METHODS:

Canine internal mammary artery segments (with and without intact endothelium) were precontracted with norepinephrine and sonicated 3 seconds in organ chambers with ultrasonic coagulating shears (Harmonic Scalpel; Ethicon Endo-Surgery, Cincinnati, OH) functioning at level 2. Vessel tension was continuously measured to examine vasoactivity in response to sonication alone (control) or with N(รน)-Nitro-l-arginine (l-NNA) and indomethacin added to the chamber medium individually or in combination. Tissue heating, acoustic pressure, and endothelial damage as detected by scanning electron micrography were also assessed.

RESULTS:

In vitro sonication with the Harmonic Scalpel induced predominately endothelium-dependent internal mammary artery vasorelaxation but a small endothelium-independent contribution was also observed. Early vasorelaxation (1 minute after stimulus) was maximally inhibited by l-NNA alone and in combination with indomethacin. Relaxation during this period was insignificantly affected by indomethacin alone. Only the combination of l-NNA and indomethacin maximally inhibited late vasorelaxation (5 minutes after stimulus), whereas inhibitory effects of l-NNA diminished during this time period. Indomethacin inhibited relaxation substantially during this phase, although significantly less than did l-NNA alone. The Harmonic Scalpel minimally heated the tissue surface (0.3 +/- 0.03 degrees C) and did not disrupt endothelial cell integrity while operating at 50 mW/cm(2) intensity (acoustic pressure 40 kPa).

CONCLUSIONS:

Sonication induces vasorelaxation almost completely by time-dependent endothelial nitric oxide and prostacyclin release, which appears unrelated to tissue heating or endothelial architectural disruption.

PMID:
14726048
[Indexed for MEDLINE]

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