A polypeptide (AP-A) from sea anemone (Anthopleura xanthogrammica) with potent positive inotropic action

Anthopleurin-A (AP-A), a polypeptide with MW ca. 5500 (53 amino acids), isolated from the sea anemone, Anthopleura xanthogrammica (Brandt), elicited a potent positive inotropic effect but without an accompanying chronotropic effect on the isolated cardiac muscles of rat, rabbit, guinea pig and cat. Similarly in dogs and cats in situ, i.p. injections of AP-A increased the contractile force without effect on heart rate or blood pressure. The cardiotonic potency for AP-A was equivalent to that of isoproterenol but much greater than that for ouabain or glucagon on the isolated cardiac muscle. AP-A increased the contractile force (cardiac output) and decreased atrial pressure in dog heart during pentobarbital-induced failure. This inotropic effect was not inhibited by propranolol pretreatment. The Ca++ requirement to restore the contractile force was less in AP-A-treated than in ouabain or isoproterenol-treated tissues. After AP-A treatment, the cardiac contractility was more resistant to hypoxia and to low or high temperature stress than ouabain-treated or control preparations. AP-A at 5 10(-9) M increased the duration of the action potential, its mean rate of rise and conduction in the guinea-pig atria and ventricles. At the maximum effective concentration, AP-A did not inhibit Na+, K+-activated adenosine triphosphatase, phosphodiesterase (high Km and low Km) and cyclic 3',5'-adenosine monophosphate content of guinea-pig heart. AP-A (5 X 10(-8) to 5 X 10(-7) M) neither contracted nor relaxed the isolated vascular smooth muscle. The results suggest that AP-A may be useful in the clinical management of cardiac failure and as an experimental tool to study the pharmacology and physiology of cardiac muscle.

Pathological studies on the intracerebral and retinal arteries in cerebrovascular and noncerebrovascular diseases

Histological examinations of the intracerebral and retinal arteries were preformed in patients who had cerebrovascular disease and in those cases who did nott. Fibrinoid degeneration, fibrous nodule, and splitting, which are most frequently found in putamen, thalamus and pons, are thought to be the main changes in cerebral hemorrhage and infarction. Fibrous and fibro-hyalinoid thickenings of the retinal arteries were found mainly in the neighboring region of the optic disk, which reflects the changes of the intracerebral arteries. Hyalinoid thickening was found in the ora serrata, which does not reflect the changes of the intracerebral arteries. Our results suggest that patients with these retinal artery changes in the region near the optic disk if moderate to severe have an increased risk of having or incurring cerebral hemorrhage and infarction, but the arterial changes in the ora serrata do not always indicate risk of cerebral hemorrhage and infarction.

Acute changes in blood pressure following vascular diseases in the brain stem

The relationship of the type of acute change in blood pressure to the site of the brain lesion, following cerebral hemorrhage and infarction, were studied in 108 patients in whom autopsy was performed. No significant changes in blood pressure were observed in cases with lesions localized rostral to the midbrain and in the medulla oblongata. The pressor response characteristic in primary pontine lesions, either hemorrhage or infarction, also was demonstrated in the cerebral hemorrhage with fourth ventricular and pontine extension. Blood pressure elevation was more marked with tegmental pontine lesions than when the lesion was in the basilar pons. Extension of the lesion into neighboring portions of the pons did not cause further change in blood pressure. The present results seem to suggest a positive role of the caudal brain stem, especially the pons, in the blood pressure elevation following the cerebrovascular accidents.