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Gender differences in heat‐induced attenuation of vasoconstriction
Author(s) -
Eisenhauer Jessica A,
Kluess Heidi A,
Anton Maria M,
DeLorey Darren S,
Buckwalter John B,
Clifford Philip S
Publication year - 2008
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.22.1_supplement.745.2
Subject(s) - vasoconstriction , phenylephrine , electrical impedance myography , medicine , endocrinology , stimulation , agonist , femoral artery , chemistry , vasodilation , receptor , blood pressure
The purpose of the study was to determine if heat attenuates sympathetic vasoconstriction in females as it does in male rats (Kluess et al., 2005). Since females have higher α 1 ‐adrenergic tone than males, the hypothesis was that the magnitude of heat attenuation would be less in females. The femoral arteries from 15 female (279±11g) and 16 male (290±10g) Sprague‐Dawley rats were prepared for wire myography. Field stimulation (2–60Hz for 144 impulses) and dose response curves for the P2X agonist, αβ‐methylene ATP (mATP: 10 −7 to 10 −3 M) and the α 1 ‐agonist, phenylephrine (PE: 10 −7 to 10 −4 M) were performed at bath temperatures of 37°C and 41°C. Heat attenuated tension produced during field stimulation in both genders, but there was greater attenuation in males (−65±13% on average) compared to females (−48±10% on average; p<0.05). Heat reduced the tension produced by mATP in female and male femoral arteries, but the slope was higher in males at 41°C (1.39±0.17g/log M mATP), than females at 41°C (0.83±0.09 g/log M mATP; p=0.01). The responsiveness to phenylephrine was unaffected by heat. Skeletal muscle arteries in female rats experience modest heat attenuation, but the magnitude of change is less than for age and weight matched males. The primary mechanism for heat‐induced attenuation of vasoconstriction in the femoral artery in males and females is P2X purinergic receptors.