Gender differences in microcirculation: observation using the hamster cheek pouch.
OBJECTIVE
Estrogen has been shown to play an important protective role in non-reproductive systems, such as the cardiovascular system. Our aim was to observe gender differences in vivo with regard to the increase in macromolecular permeability and leukocyte-endothelium interaction induced by ischemia/reperfusion as well as in microvascular reactivity to vasoactive substances using the hamster cheek pouch preparation.


METHODS
Thirty-six male and 36 female hamsters, 21 weeks old, were selected for this study, and their cheek pouches were prepared for intravital microscopy. An increase in the macromolecular permeability of post-capillary venules was quantified as a leakage of intravenously injected fluorescein-labeled dextran, and the leukocyte-endothelium interaction was measured as the number of fluorescent rolling leukocytes or leukocytes adherent to the venular wall, labeled with rhodamin G, during reperfusion after 30 min of local ischemia. For microvascular reactivity, the mean internal diameter of arterioles was evaluated after the topical application of different concentrations of two vasoconstrictors, phenylephrine (α1-agonist) and endothelin-1, and two vasodilators, acetylcholine (endothelial-dependent) and sodium nitroprusside (endothelial-independent).


RESULTS
The increase in macromolecular permeability induced by ischemia/reperfusion was significantly lower in females compared with males [19 (17-22) leaks/cm2 vs. 124 (123-128) leaks/cm2, respectively, p<0.001), but the number of rolling or adherent leukocytes was not different between the groups. Phenylephrine-induced arteriolar constriction was significantly lower in females compared with males [77 (73-102)% vs. 64 (55-69)%, p<0.04], but there were no detectable differences in endothelin-1-dependent vasoreactivity. Additionally, arteriolar vasodilatation elicited by acetylcholine or sodium nitroprusside did not differ between the groups.


CONCLUSIONS
The female gender could have a direct protective role in microvascular reactivity and the increase in macromolecular permeability induced by ischemia/reperfusion.
Clinical and Experimental Research Laboratory on Vascular Biology, Biomedical Center, State University of Rio de Janeiro, Rio de JaneiroRJ, Brazil.
Diogo Guarnieri
DG
Panazzolo
Clinical and Experimental Research Laboratory on Vascular Biology, Biomedical Center, State University of Rio de Janeiro, Rio de JaneiroRJ, Brazil.
Lucia Henriques Alves da
LH
Silva
Clinical and Experimental Research Laboratory on Vascular Biology, Biomedical Center, State University of Rio de Janeiro, Rio de JaneiroRJ, Brazil.
Fátima Zely Garcia de Almeida
FZ
Cyrino
Clinical and Experimental Research Laboratory on Vascular Biology, Biomedical Center, State University of Rio de Janeiro, Rio de JaneiroRJ, Brazil.
Fernando Lencastre
FL
Sicuro
Clinical and Experimental Research Laboratory on Vascular Biology, Biomedical Center, State University of Rio de Janeiro, Rio de JaneiroRJ, Brazil.
Luiz Guilherme
LG
Kraemer-Aguiar
Clinical and Experimental Research Laboratory on Vascular Biology, Biomedical Center, State University of Rio de Janeiro, Rio de JaneiroRJ, Brazil.
Eliete
E
Bouskela
D000109:Acetylcholine / Q000494:pharmacology; D000818:Animals; D002199:Capillary Permeability; D002319:Cardiovascular System / Q000378:metabolism*; D002448:Cell Adhesion / Q000502:physiology; D002610:Cheek / Q000098:blood supply; D006224:Cricetinae; D004730:Endothelium, Vascular / Q000502:physiology; D004967:Estrogens / Q000378:metabolism*; D005260:Female; D007962:Leukocytes / Q000502:physiology; D008297:Male; D008833:Microcirculation / Q000502:physiology*; D009599:Nitroprusside / Q000494:pharmacology; D010656:Phenylephrine / Q000494:pharmacology; D015427:Reperfusion Injury / Q000378:metabolism; D012737:Sex Factors; D013997:Time Factors
D004967:Estrogens; D009599:Nitroprusside; D010656:Phenylephrine; D000109:Acetylcholine