Myogenic reactivity of rat epineurial arterioles: potential role in local vasoregulatory events

Wang, Hong Xin; Davis, Michael J.; Rajanayagam, M. A. Sharmini; Potocnik, Simon; Hill, Michael A.

doi:10.1152/ajpheart.1999.277.1.h144

Cited by 10 publications

(15 citation statements)

References 26 publications

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“…A dose of 3 ϫ 10 Ϫ7 M NE completely constricted the epineurial arterioles and terminated local blood flow in sciatic nerves. The NE-induced responses obtained in the present study were quite compatible with other reports (16,38). It has been reported that endoneurial arterioles control the blood flow of sciatic nerves as well as the epineurial arterioles (2,46).…”

Section: Discussionsupporting

confidence: 93%

“…On the other hand, superfusion with LKS did not affect the diameters of epineurial arterioles in the present study. Wang et al (38) used a physiological buffer solution bubbled with 95% N 2 -5% CO 2 to measure in vivo blood flow of rat sciatic nerves with laser Doppler flowmetry, as did the present study, which superfused them with LKS. In a study using hydrogen-clearance methods, other investigators (3) filled the measuring area of sciatic nerves with mineral oil.…”

Section: Discussionmentioning

confidence: 87%

“…Regulation of myogenic activity in peripheral nerve arterioles, however, is not fully understood. Wang et al (38) demonstrated that isolated epineurial arterioles of rats (active and passive diameters were 55 Ϯ 6 and 84 Ϯ 6 m, respectively, at 60 mmHg) show intrinsic myogenic reactivity in vitro. The diameters of sciatic nerve epineurial arterioles used in the present study were smaller (26 Ϯ 7 m; n ϭ 78) and from a more distal location than those used in the Wang et al studies (38).…”

Section: Discussionmentioning

confidence: 99%

“…Wang et al (38) demonstrated that isolated epineurial arterioles of rats (active and passive diameters were 55 Ϯ 6 and 84 Ϯ 6 m, respectively, at 60 mmHg) show intrinsic myogenic reactivity in vitro. The diameters of sciatic nerve epineurial arterioles used in the present study were smaller (26 Ϯ 7 m; n ϭ 78) and from a more distal location than those used in the Wang et al studies (38). In the present study, superfusion of nifedipine (a Ca 2ϩ -channel blocker) onto sciatic nerves in the presence of LKS significantly dilated the epineurial arterioles.…”

Section: Discussionmentioning

confidence: 99%

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High oxygen tension constricts epineurial arterioles of the rat sciatic nerve via reactive oxygen species

Sakai

Mizuno²,

Ono³

et al. 2007

American Journal of Physiology-Heart and Circulatory Physiology

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Sakai N, Mizuno R, Ono N, Kato H, Ohhashi T. High oxygen tension constricts epineurial arterioles of the rat sciatic nerve via reactive oxygen species. Am J Physiol Heart Circ Physiol 293: H1498-H1507, 2007. First published May 18, 2007; doi:10.1152/ajpheart.01190.2006.-Microcirculation of the sheath of the rat sciatic nerve fiber was investigated by using an intravital microscope, and changes in the diameter of the epineurial arterioles in response to highly oxygenated Krebs-bicarbonate solution were evaluated. Superfusion of low-oxygen (0%) Krebs-bicarbonate solution (LKS) onto rat sciatic nerves did not affect changes in the diameter of the arterioles. Nifedipine, a Ca 2ϩ -channel blocker, caused a dosedependent dilation of the epineurial arterioles in LKS. In contrast, superfusion of high-oxygen (21%) Krebs-bicarbonate solution (HKS) onto rat sciatic nerves significantly constricted the epineurial arterioles in a time-dependent manner. The HKS-induced constriction of the epineurial arterioles was significantly reduced by treatment with 120 U/ml superoxide dismutase (SOD) alone or 5,000 U/ml catalase alone. In the presence of 120 U/ml SOD plus 5,000 U/ml catalase, 10 Ϫ4 M tempol, 10 Ϫ6 M diphenyleneiodium, 2 ϫ 10 Ϫ4 M apocynin, or 10 Ϫ6 M allopurinol, the HKS-induced constriction of the epineurial arterioles completely disappeared. These results suggest that superfusion of highly oxygenated solution onto rat sciatic nerves constricts the epineurial arterioles through reactive oxygen species (ROS), including superoxide and hydrogen peroxide, and that production of superoxide involves a NADPH oxidase-or xanthine oxidase-dependent pathway. In conclusion, ROS play significant roles in the regulation of microcirculation of rat sciatic nerves in vivo. peripheral nerves; microcirculation; superoxide; hydrogen peroxide BLOOD SUPPLY TO PERIPHERAL nerves is important to maintain the functions of the nerve fibers. The disturbance of blood circulation within sciatic nerves produces dysfunction such as suppression of motor nerve conduction velocity (2, 3). It has become clear that pathogenesis of diabetic neuropathy is associated with a reduction of blood flow in sciatic nerves in diabetic animals and humans (14, 34). Thus understanding the regulation of blood flow in sciatic nerves is quite important for diagnosis and treatment of diabetic neuropathy.Laser Doppler flowmetry and hydrogen clearance are methods available to study the blood flow in sciatic nerves in vivo (2-4, 16, 17, 30, 33, 35, 46). From the use of these methods, it is known that the epineurial and endoneurial arterioles of sciatic nerves play crucial roles in the regulation of microcirculation. Although these methods are capable of measuring local blood flow in the sheath of sciatic nerves in vivo, changes in the diameter of the arterioles in the sheath of sciatic nerves could not be identified. It is necessary to measure changes in the diameter of the arterioles in vivo, because the arterioles and small arteries are resistant vessels, and changes in the...

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Section: Discussionsupporting

confidence: 93%

Section: Discussionmentioning

confidence: 87%

Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

See 2 more Smart Citations

High oxygen tension constricts epineurial arterioles of the rat sciatic nerve via reactive oxygen species

Sakai

Mizuno²,

Ono³

et al. 2007

American Journal of Physiology-Heart and Circulatory Physiology

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“…Nevertheless, normalization of the data in Fig. 2B to PD at 70 mmHg [i.e., classic myogenic reactivity curves (48)] reveals that the OH rat arteries exhibited significantly augmented myogenic constriction (Fig. 4C).…”

Section: Myogenic Responsesmentioning

confidence: 99%

Low-dose ouabain constricts small arteries from ouabain-hypertensive rats: implications for sustained elevation of vascular resistance

Zhang¹,

Hamlyn²,

Karashima³

et al. 2009

American Journal of Physiology-Heart and Circulatory Physiology

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Low-dose ouabain constricts small arteries from ouabain-hypertensive rats: implications for sustained elevation of vascular resistance. Am J Physiol Heart Circ Physiol 297: H1140 -H1150, 2009. First published July 17, 2009 doi:10.1152/ajpheart.00436.2009.-Prolonged ouabain administration to normal rats causes sustained blood pressure (BP) elevation. This ouabain-induced hypertension (OH) has been attributed, in part, to the narrowing of third-order resistance arteries (ϳ320 m internal diameter) as a result of collagen deposition in the artery media (see Ref. 6). Here we describe the structural and functional properties of fourth-order mesenteric small arteries from control and OH rats, including the effect of low-dose ouabain on myogenic tone in these arteries. Systolic BP in OH rats was 138 Ϯ 3 versus 124 Ϯ 4 mmHg in controls (P Ͻ 0.01). Pressurized (70 mmHg) control and OH arteries, with only a single layer of myocytes, both had ϳ165-m internal diameters and ϳ20-m wall thicknesses. Even after fixation, despite vasoconstriction, the diameters and wall thicknesses did not differ between control and OH fourth-order arteries, whereas in third-order arteries, both parameters were significantly smaller in OH than in controls. Myogenic reactivity was significantly augmented in OH fourth-order arteries. Nevertheless, phenylephrine-(1 M) and high K ϩ -induced vasoconstrictions and acetylcholine-induced vasodilation were comparable in control and OH arteries. Vasoconstrictions induced by 5 M phenylephrine and by 10 mM caffeine in Ca 2ϩ -free media indicated that releasable sarcoplasmic reticulum Ca 2ϩ stores were normal in OH arteries. Importantly, 100 nM ouabain constricted both control and OH arteries by ϳ26 m, indicating that this response was not downregulated in OH rats. This maximal ouabain-induced constriction corresponds to a ϳ90% increase in resistance to flow in these small arteries; thus ouabain at EC 50 of ϳ0.66 nM should raise resistance by ϳ35%. We conclude that dynamic constriction in response to circulating nanomolar ouabain in small arteries likely makes a major contribution to the increased vascular tone and BP in OH rats. myogenic reactivity; resistance artery OUABAIN, A MAMMALIAN adrenocortical hormone (4,20,21,28), apparently plays an important role in the pathogenesis of hypertension in humans and rodents. About 50% of patients with essential hypertension and a majority of patients with adrenocortical adenomas and hypertension have elevated plasma endogenous ouabain (EO) (42,45). In normal humans, ouabain infusion increases peripheral vascular resistance, reduces blood flow, and elevates blood pressure (BP) (35, 47).Moreover, high-dietary salt increases plasma EO levels in normal men (32).Elevated EO levels are also observed in rats with DOCA-salt hypertension (20), reduced renal mass hypertension (24), and Milan strain hypertension (14). Additionally, the chronic treatment of normal rats and mice with ouabain elevates BP, i.e., ouabain-induced hypertension (OH) (12, 33, 50). Although digoxin, lik...

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The Microcirculation of Peripheral Nerves

Boissaud-Cooke

Pidgeon

Tunstall

2015

Nerves and Nerve Injuries

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Myogenic reactivity of rat epineurial arterioles: potential role in local vasoregulatory events

Cited by 10 publications

References 26 publications

High oxygen tension constricts epineurial arterioles of the rat sciatic nerve via reactive oxygen species

High oxygen tension constricts epineurial arterioles of the rat sciatic nerve via reactive oxygen species

Low-dose ouabain constricts small arteries from ouabain-hypertensive rats: implications for sustained elevation of vascular resistance

The Microcirculation of Peripheral Nerves

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