Regulating effects of vascular endothelial growth factor and ANG II on frog's pericardial stomata, mesothelium and angiogenesis.
OBJECTIVE
To observe the regulating effects of vascular endothelial growth factor (VEGF) and angiotensin II (ANG II) on the frog's pericardium, lymphatic stomata and angiogenesis so as to reveal their effects and mechanism on the mesothelial permeability, lymphatic stoma regulation and myocardial hypertrophy.


METHODS
VEGF and ANG II were injected into the frog's peritoneal cavity so as to examine the changes of the pericardial stromata by using transmission electron microscopy, scanning electron microscopy and computerized imaging analysis.


RESULTS
Scattered distributed pericardial stomata were found on the parietal pericardium of the frog with a few sinusoid mesothelial cells, whose blood supply was directly from the cardiac chambers flowing into the trabecular spaces of the myocardium (because there are no blood vessels in the myocardium of the frog). The average diameters of the pericardial stomata in VEGF and ANG II groups were 1. 50 microm and 1.79 microm respectively, which were much larger than those in the control group (0.72 microm, P < 0.01); the average distribution densities of the stomata were 8. 25/0.1 mm2 and 12.80/0.1 mm2 in VEGF and ANG II groups, which were also much higher than those in the control group (3.57/0.1 mm2, P < 0.01); the sinusoid areas in VEGF and ANG II groups were 2442.95 microm2/0.1 mm2 and 2121.79 microm2/0.1 mm2, which were larger than that in the control group (995.08 microm2/0.1 mm2 , P < 0.01); no angiogenesis was found in the frogs of the experimental groups.


CONCLUSIONS
VEGF and ANG II could strongly regulate the pericardial stomata by increasing their numbers and openings with larger diameters and higher distribution density. They could also increase the sinusoid areas with the result of the higher permeability of the pericardium, which clearly indicated that VEGF and ANG II could speed up the material transfer of the pericardial cavity and play an important role in preventing myocardial interstitial edema. Yet there was no strong evidence to show the angiogenesis in the myocardium.
Li
J
J
Department of Lymphology, Zhejiang University School of Medicine, Hangzhou 310031.
Zhou
J
J
Tota
B
B
Scalia
G
G
Gattuso
A
A
D000804:Angiotensin II / Q000494:pharmacology*; D000818:Animals; D004847:Epithelial Cells / Q000187:drug effects; D007091:Image Processing, Computer-Assisted; D008855:Microscopy, Electron, Scanning; D010496:Pericardium / Q000187:drug effects / Q000648:ultrastructure*; D011893:Rana esculenta; D011897:Random Allocation; D042461:Vascular Endothelial Growth Factor A / Q000494:pharmacology*
D042461:Vascular Endothelial Growth Factor A; D000804:Angiotensin II