Dilatation of pial arterial vessels in hypercapnia and in acute hypertension.

Pial arterial vessels were inspected in hypercapnia (PaCO2 97 +/- 9 (S.E.) mmHg) and in acute hypertension induced by 5 microgram kg-1 noradrenaline i.v. (mean arterial pressure 210 +/- 5 mmHg) by means of a cranial window. The diameter of arterial vessels with a resting diameter of 10 to 150 micrometer was measured either from photographs or by aid of an image splitting eyepiece. Arterioles with a resting diameter less than or equal to 30 micrometer exhibited the highest degree of dilatation both in hypercapnia and acute hypertension. The mean dilatation was higher in hypertension than in hypercapnia in vessels of all sizes, the difference being statistically significant in arterioles up to 50 micrometer resting diameter.

[1]  B. Johansson,et al.  ON THE PATHOPHYSIOLOGY OF THE INCREASED CEREBROVASCULAR PERMEABILITY IN ACUTE ARTERIAL HYPERTENSION IN CATS , 1972, Acta neurologica Scandinavica.

[2]  C. Nordborg,et al.  The ratio between thickness of media and internal radius in cerebral, mesenteric and renal arterial vessels in spontaneously hypertensive rats. , 1979, Clinical science.

[3]  R. Vines.  ON THE APPEARANCE OF THE BLOOD OF ANIMALS UNDER DIPFERENT STATES OF EXCITEMENT. , 1828 .

[4]  B. Johansson,et al.  Cerebral Vasomotor Reactivity in Normotensive and Spontaneously Hypertensive Rats , 1979, Stroke.

[5]  J Linder,et al.  Sympathetic control of cerebral blood flow in acute arterial hypertension. , 1976, Acta physiologica Scandinavica.

[6]  D. Denny-Brown,et al.  The cerebral arterioles in experimental hypertension. I. The nature of arteriolar constriction and its effects on the collateral circulation. , 1966, The American journal of pathology.

[7]  Pathogenesis of hypertensive encephalopathy. , 1973, Lancet.

[8]  D. Graham,et al.  Effects of Acutely Induced Hypertension in Cats on Pial Arteriolar Caliber, Local Cerebral Blood Flow, and the Blood‐Brain Barrier , 1976, Circulation research.

[9]  F B BYROM,et al.  The pathogenesis of hypertensive encephalopathy and its relation to the malignant phase of hypertension; experimental evidence from the hypertensive rat. , 1954, Lancet.

[10]  L. Auer.  Pial arterial reactions to hyper- and hypocapnia: a dynamic experimental study in cats. , 1978 .

[11]  Ludwig Michael Auer,et al.  The Pathogenesis of Hypertensive Encephalopathy , 1978, Acta Neurochirurgica.

[12]  B. Johansson.  REGIONAL CEREBRAL BLOOD FLOW IN ACUTE EXPERIMENTAL HYPERTENSION , 1974, Acta neurologica Scandinavica.

[13]  M. Purves,et al.  Control of cerebral blood vessels: Present state of the art , 1978, Annals of neurology.