Microvascular reactivity in experimental diabetes: responses of male and female rats.
OBJECTIVE
To study the influence of sex on the responses of microvessels to vasoactive agents in experimental diabetes.


METHODS
Diabetes was induced by alloxan (40 mg/kg, iv) in male and female Wistar rats (8-10-week-old).


METHODS
Using an image splitter television microscope, mesenteric arteriolar and venular diameter changes induced by topically applied vasoactive agents (histamine, bradykinin, platelet activating factor-PAF, acetylcholine, sodium nitroprusside, noradrenaline and angiotensin II) were examined.


RESULTS
Whereas the vasoconstrictor response to noradrenaline was equivalent in normal and diabetic animals, either female or male rats, an increased vasoconstrictor response to angiotensin II was observed in male but not in female diabetic rats in comparison with respective controls. Similarly to that observed in males, the dilator response of microvessels to topically applied bradykinin, histamine and PAF was impaired in female diabetic rats. Whereas reversal of the impaired responses to these agents was obtained by acute treatment of diabetic animals with insulin the altered responses to angiotensin II observed in male diabetic rats were not corrected. Differently from that observed in males, impaired response of microvessels to acetylcholine but not to sodium nitroprusside was observed in female diestrous diabetic rats; acute insulin treatment corrected it.


CONCLUSIONS
We conclude that not all the alterations of the microvascular reactivity and the correction by insulin are gender dependent in diabetes.
Toledo
D P
DP
Department of Pharmacology, Institute of Biomedical Sciences, University of São Paulo, Av. Prof. Lineu Prestes, 1524, Cidade Universitária, 05508-900, São Paulo, Brazil.
Akamine
E
E
Nigro
D
D
Passaglia
R C T
RC
Carvalho
M H C
MH
Fortes
Z B
ZB
D000109:Acetylcholine / Q000494:pharmacology; D000804:Angiotensin II / Q000494:pharmacology; D000818:Animals; D001835:Body Weight / Q000187:drug effects; D001920:Bradykinin / Q000494:pharmacology; D003921:Diabetes Mellitus, Experimental / Q000503:physiopathology*; D030762:Estrous Cycle / Q000187:drug effects; D005260:Female; D006632:Histamine / Q000494:pharmacology; D007004:Hypoglycemic Agents / Q000494:pharmacology; D007328:Insulin / Q000494:pharmacology; D008297:Male; D008833:Microcirculation / Q000033:anatomy & histology / Q000187:drug effects / Q000503:physiopathology; D009599:Nitroprusside / Q000494:pharmacology; D009638:Norepinephrine / Q000494:pharmacology; D009929:Organ Size / Q000187:drug effects; D010972:Platelet Activating Factor / Q000494:pharmacology; D051381:Rats; D017208:Rats, Wistar; D012727:Sex Characteristics; D014599:Uterus / Q000187:drug effects; D014662:Vasoconstrictor Agents / Q000494:pharmacology; D014665:Vasodilator Agents / Q000494:pharmacology
D007004:Hypoglycemic Agents; D007328:Insulin; D010972:Platelet Activating Factor; D014662:Vasoconstrictor Agents; D014665:Vasodilator Agents; D000804:Angiotensin II; D009599:Nitroprusside; D006632:Histamine; D000109:Acetylcholine; D001920:Bradykinin; D009638:Norepinephrine