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Interaction between conducted vasodilation and sympathetic nerve activation in arterioles of hamster striated muscle
1John B. Pierce Laboratory, Yale University School of Medicine, New Haven, CT 06519, USA.
Insights
Sympathetic nerve activity influences vasodilation conduction in arterioles. Perivascular nerves modulate cell-to-cell communication along the arteriolar wall, impacting blood flow regulation.
Area of Science:
- Physiology
- Cardiovascular Research
- Neuroscience
Background:
- Sympathetic nerve activity plays a crucial role in regulating vascular tone and blood flow.
- The mechanisms by which sympathetic nerves influence conducted responses along the arteriolar wall are not fully understood.
- Understanding these interactions is vital for comprehending microcirculation regulation in striated muscle.
Purpose of the Study:
- To test the hypothesis that sympathetic nerve activity affects the conduction of vasodilation along the arteriolar wall.
- To investigate the role of alpha-adrenoceptors in mediating sympathetic nerve-induced vasoconstriction and its effect on conducted vasodilation.
- To elucidate the influence of perivascular nerves on arteriolar cell-to-cell communication.
Main Methods:
- Studied arterioles in the superfused cremaster muscle of anesthetized male hamsters.
- Utilized perivascular nerve stimulation (PNS) to activate sympathetic nerves.
- Induced local and conducted vasodilation using acetylcholine (ACh) via microiontophoresis, recording diameter responses.
Main Results:
- Perivascular nerve stimulation induced frequency-dependent vasoconstriction, significantly attenuated by alpha-adrenoceptor blockade.
- Conducted vasodilation was attenuated during sympathetic nerve stimulation, an effect reversed by alpha-adrenoceptor blockade.
- Conducted vasodilation reciprocally diminished sympathetic nerve-induced vasoconstriction; neural blockade enhanced conducted vasodilation.
Conclusions:
- Perivascular nerves in striated muscle significantly influence the conduction of vasodilation along the arteriolar wall.
- Sympathetic nerve activity modulates arteriolar cell-to-cell communication, affecting both vasoconstriction and vasodilation.
- These findings highlight a dynamic interplay between neural control and vascular signaling in microcirculation.
Abstract:
We tested the hypothesis that sympathetic nerve activity can influence the conduction of vasodilation along the arteriolar wall. Arterioles in the superfused cremaster muscle of anesthetized male hamsters (n = 21, 109 +/- 4 g) were studied. Microelectrodes were positioned adjacent to the distal end of primary arterioles to stimulate sympathetic nerves throughout arteriolar networks (perivascular nerve stimulation [PNS]). Microiontophoresis micropipettes (tip outer diameter, 1 to 2 microns) filled with acetylcholine (ACh, 1 mol/L) were positioned adjacent to the wall of second-order (2A) or third-order (3A) arterioles approximately 1 mm distal to their origin to induce local and conducted vasodilation; diameter responses were recorded at the micropipette tip and at vessel origins, respectively. For 2A and 3A arterioles (resting diameters, 15 to 54 and 9 to 30 microns, respectively), vasoconstriction with PNS was frequency dependent (0.5 to 32 Hz); this was attenuated by 65% (P < .05) with alpha-adrenoceptor blockade (phentolamine, 1 mumol/L). Conducted vasodilation was attenuated by > 40% during 16-Hz PNS (P < .05); this effect was reversed by phentolamine. In a reciprocal fashion, conducted vasodilation diminished PNS-induced vasoconstriction by approximately 50% (P < .05). Elevating oxygen (from 0% to 10%) in the superfusion solution induced vasoconstriction similar to that with 16-Hz PNS yet had no effect on conduction. Neural blockade with tetrodotoxin (1 mumol/L) eliminated PNS-induced vasoconstriction and enhanced (P < .05) conducted vasodilation. These findings indicate that perivascular nerves in striated muscle can influence cell-to-cell communication along the arteriolar wall both at rest and during enhanced sympathetic activity.(ABSTRACT TRUNCATED AT 250 WORDS)