Dependency of Pial Arterial and Arteriolar Diameter on Perivascular Osmolarity in the Cat

Wahl, Michael; Kuschinsky, Wolfgang; Bosse, O.; Thurau, Klaus

doi:10.1161/01.res.32.2.162

Cited by 100 publications

(38 citation statements)

References 40 publications

(47 reference statements)

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“…Changes in local steady-state conditions, if only from the osmotic point of view, might be the main factor responsible for the antagonistic effect of histamine and bradykinin toward the vasoconstrictor response to noradrenaline. Microscopic studies show that the (n =6) direct application of hypertonic solutions to cerebral (Wahl, Kuschinsky, Bosse & Thurau, 1973) and muscle vessels (Gray, 1971) causes their relaxation.…”

Section: Discussionmentioning

confidence: 99%

Vascular reactivity in diabetes mellitus: role of the endothelial cell

Fortes

Lerne

Scivoletto

1983

British J Pharmacology

130

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1 The response to vasoactive agents of microvessels in situ and large arteries in vitro was compared in normal and alloxan-diabetic rats. 2 Noradrenaline was equally effective in evoking a constrictor response of mesenteric microvessels in normal and diabetic animals. 3 The constrictor response to a standard amount of noradrenaline in such vessels was fully antagonized by acetylcholine or papaverine, the minimum effective doses being equivalent in normal and diabetic animals. In contrast, the minimum doses of histamine or bradykinin, effective in normal animals, had to be increased about 20 fold to be active in diabetic animals. 4 Increased osmolarity of extracellular fluid caused a significant and equivalent increase in latency of the vasoconstrictor response of microvessels to noradrenaline in normal and diabetic animals. 5 Concentration-effect curves, constructed from the response of isolated aortae to noradrenaline, were similar in normal and diabetic animals, provided the endothelium was removed. Diabetes only affected preparations in which the endothelium was left intact. In these, the median effective concentrations of noradrenaline were greatly increased in comparison with normal values. 6 Precontracted aortae from normal and diabetic animals were equally relaxed by acetylcholine and histamine, provided the endothelium was left intact. Loss of the relaxant response of the preparations in all groups of animals was observed following removal of endothelial cells. 7 It is suggested that different mechanisms may be involved in the effects of vasodilator agents on large arteries in vitro or small vessels in situ. Histamine and bradykinin which are potent permeability-increasing factors, may antagonize the vasoconstrictor response of microvessels to noradrenaline through an action on endothelial cells with increased vascular permeability and temporary changes in composition of extracellular fluid. The reactive process of endothelial cells to permeability factors was affected by diabetes mellitus. However, the response of microvessels to acetylcholine and papaverine which are devoid of permeability-increasing properties, was not influenced by diabetes.

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Section: Discussionmentioning

confidence: 99%

Vascular reactivity in diabetes mellitus: role of the endothelial cell

Fortes

Lerne

Scivoletto

1983

British J Pharmacology

130

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“…It had a lower osmolality, a lower Po, and a higher potassium concentration. In other experiments Wahl and his colleagues 20 found that a decrease in osmolality from 315 to 280 mOsm per kilogram would produce a 20% reduction in pial arterial diameter. Similarly, the same investigators found that increase in potassium ion concentration from 3 to 5 mEq per liter would produce a 20% increase in pial arterial diameter.…”

Section: Determinants Of Response Of Pial Arteriesmentioning

confidence: 92%

Determinants of Response of Pial Arteries to Norepinephrine and Sympathetic Nerve Stimulation

Wei

Raper

Kontos

et al. 1975

Stroke

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Determinants of Response of Pial Arteries to Norepinephrine and Sympathetic Nerve Stimulation• Feline pial arteries larger than 100 M in diameter constricted in response to cervical sympathetic nerve stimulation or in response to topical application of norepinephrine. Smaller pial arteries were unresponsive to norepinephrine. This unresponsiveness persisted when norepinephrine was dissolved in CSF with high calcium ion concentration, or in CSF with both high calcium ion and zero magnesium ion concentration, or when it was dissolved in the acid fluid used by Wahl et al. and applied by constant infusion or by intermittent application. Comparison of the responses of the larger pial vessels to norepinephrine and to sympathetic nerve stimulation suggests that maximal activation of sympathetic nerves achieves a concentration of released norepinephrine equal to 5.9 X 10 8 M. The constriction of the larger pial vessels in response to sympathetic nerve stimulation could account for modest reductions in cerebral blood flow.Additional Key Words cat vasoconstriction catecholamines neurogenic control of cerebral blood flow• Despite extensive study there is still considerable disagreement concerning the physiological importance of neurogenic control of cerebral blood vessels. 13Studies utilizing pressure and flow measurements have yielded contradictory results. Much of the disagreement is related to problems with the techniques of measuring blood flow. 2 A different approach, not subject to these objections, is the direct observation of the blood vessels on the surface of the brain. In an earlier study 4 we were unable to establish a physiological basis for neurogenic control of the cerebral circulation via changes in the activity of adrenergic fibers innervating the smaller cerebral arterioles. In that study we found that, although pial arteries smaller than 100 M in diameter were richly innervated by adrenergic nerve fibers, they were unresponsive to high concentrations of topically applied norepinephrine and isoproterenol and were equally unresponsive to maximal electrical stimulation of the cerebral sympathetic nerves. These results were in apparent conflict with the findings of other investigators who had shown significant vasoconstriction in response to either epinephrine or

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“…The technique of perivascular application is one based on that developed by Wahl, Kuschinsky, Bosse & Thurau (1973) and has been previously described (Harper & MacKenzie, 1977 b Krebs solution did not affect the vascular diameter. The results were expressed as a percentage change since the reaction was found to be independent of the diameter over the range investigated.…”

Section: Cat Experimentsmentioning

confidence: 99%

Effect of adenosine triphosphate and some derivatives on cerebral blood flow and metabolism.

Forrester¹,

Harper²,

MacKenzie³

et al. 1979

The Journal of Physiology

123

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SUMMARY1. Responses of cerebral blood vessels to peri-and intravascular doses of ATP (adenosine triphosphate) and some derivatives were studied in cat and baboon.2. Perivascular application of ATP to cat pial arterioles gave a threshold dilatory effect at a concentration of 10-11 M. This figure is comparable to the amount of ATP calculated to be released from electrically stimulated brain slices.3. It is concluded that adenine nucleotides have a major role to play in the local control of cerebral blood flow. 4. Intracarotid injection of ATP showed a calculated threshold effect at 4 x lVh8 M in the cat and 4 x 10-9 M in the baboon.5. The threshold response of the vasculature to intracarotid adenosine lay between 4 x 10-7 M and 4 x 106 M in the baboon. Little effect was produced with AMP, pyrophosphate and inorganic phosphate.6. Intracarotid ATP increased the oxygen consumption of the baboon brain parenchyma. This effect was attributed in part to an elevation of the cellular cyclic AMP levels.7. Osmotic disruption of the blood-brain barrier in baboon did not affect the vasodilatory or metabolic effect of intracarotid ATP.8. It is postulated that circulating purine compounds mediate a form of metabolic communication in the body. Also, release of purine compounds from active local nerves might influence cerebral blood flow.

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Dependency of Pial Arterial and Arteriolar Diameter on Perivascular Osmolarity in the Cat

Cited by 100 publications

References 40 publications

Vascular reactivity in diabetes mellitus: role of the endothelial cell

Vascular reactivity in diabetes mellitus: role of the endothelial cell

Determinants of Response of Pial Arteries to Norepinephrine and Sympathetic Nerve Stimulation

Effect of adenosine triphosphate and some derivatives on cerebral blood flow and metabolism.

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