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Role of Endothelium‐Derived Relaxing Factors in Arteriolar Dilation During Muscle Contraction Elicited by Electrical Field Stimulation
Author(s) -
Saito Yuichiro,
Eraslan Akin,
Hester Robert L.
Publication year - 1994
Publication title -
microcirculation
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.793
H-Index - 83
eISSN - 1549-8719
pISSN - 1073-9688
DOI - 10.3109/10739689409148274
Subject(s) - contraction (grammar) , stimulation , dilation (metric space) , muscle contraction , endothelium , medicine , electrical muscle stimulation , cardiology , chemistry , mathematics , combinatorics
Objective: To determine the contribution of either endothelium‐derived nitric oxide (EDNO) or prostaglandins in the functional vasodilation of first‐order arterioles of the hamster cremaster muscle. Methods: First‐order arterioles dilated from 72 ± 3 μm to 93 ± 4 μm in response to contraction of the cremaster muscle for 1 min ( n = 7). After EDNO inhibition by topical application of 10 μM N ω ‐nitro‐l‐arginine methyl ester (L‐NAME), the resting diameter decreased to 66 ± 3 μm and functional dilation was attenuated to 75 ± 3 μm ( P < 0.05). When the arteriolar diameter was returned to the control values by the addition of sodium nitroprusside, an NO donor, into the superfusion solution ( n = 7), functional dilation was similar to that observed before EDNO inhibition (91 ± 3 μm vs. 89 ± 3 μm, P > 0.05). To evaluate whether the vasoconstrictor effect of L‐NAME on functional dilation is same as other vasoconstrictors, norepinephrine was applied on the cremaster muscle to induce a vasoconstriction (72 ± 2 to 66 ± 1 μm, n = 7) equivalent to L‐NAME. Results: Norepinephrine treatment attenuated functional dilation to 77 ± 3 μm which was to a level similar to L‐NAME treatment ( P > 0.05). Inhibition of prostaglandin synthesis by topical application of indomethacin (28 μM) resulted in no significant changes in the resting diameter but functional vasodilation was attenuated from 89 ± 2 to 81 ± 3 μm ( n = 7, P < 0.05). Conclusions: These results suggest that EDNO is important for the resting tone of arterioles and that prostaglandins are important in modulating the functional dilation of the first‐order arterioles in the hamster cremaster muscle.