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At least 289 records · Page 16Linked to original sources
PubMed1984

Vasoactive agonists prevent erythrocyte extravasation in thrombocytopenic hamsters.

The mediating action of selected vasoactive amines and their respective antagonists on vascular fragility, visible as cutaneous petechiae, was assayed with thrombocytopenic (TCP) hamsters. Serotonin (5-HT), norepinephrine (NE), epinephrine, dopamine and isoproterenol administered IP reduced petechiae significantly within 10 min; phenylephrine had no effect. Of the natural amines, 5-HT and NE were most effective in reducing petechial sensitivity to values obtained with untreated, normal animals; hence these two amines only were tested pharmacologically. Pretreatment of TCP animals with Ketanserin or propranolol, administered IP or IV, abolished any petechial inhibitory action of 5-HT and NE respectively; pretreatment with phenoxybenzamine reduced significantly the NE inhibition of petechiae, but to a lesser degree than propranolol. In contrast, atenolol, prazosin and yohimbine had no significant effect. Ketanserin abolished the action of NE, but adrenoceptor blockers had no effect on 5-HT-treated TCP hamsters. The results suggest that 5-HT and NE inhibition of petechiae may be receptor-mediated and that there may be receptor interaction. This was supported by the observation that non-additive subthreshold doses of 5-HT and NE, which individually did not prevent petechial formation in TCP hamsters, when combined totally inhibited petechiae. The theorized importance of endogenous 5-HT and NE to maintain postcapillary venule junctional integrity (site of petechial hemorrhaging) was also demonstrated by treating normal hamsters with drugs known to block or antagonize either 5-HT or NE uptake. In every instance petechial sensitivity rapidly occurred, and the loss of microvascular integrity in Ketanserin-treated hamsters mimicked quantitatively the petechial sensitivity observed with TCP animals.

Animals↗
PubMed1976

[Thromboses and haemorrhages in geriatrics (author's transl)].

In elderly patients thromboses are especially important because of their frequency and consequences (invalidity) often demanding measures of rehabilitation. In thrombophilia there are prophylactic measures necessary founding upon new perceptions on pathogenesis (vascular wall factors; rheologic and microcirculatory factors and factors of hemostasis: increasing of factor VIII; decreasing of antithrombin III; hypofibrinolysis; increased aggregation of thrombocytes). In prophylaxis you should influence the predisposing factors (hypertension, diabetes, arteriosclerosis, adipositas), use dietetic and hygienic measures and also from the pharmalogical point medicines with complex effect, which not only act on one factor (blood coagulation) like the anticoagulants, but also on other pre-disposing factors; and at the same time activate the fibrinolysis and stop the aggregation of thrombocytes. Thrombolytica should be used in elderly patients with precaution. In hemorrhages in the age especially capillary protecting medicaments should be used to correct the increased fragility of capillaries. Of there is at the some time a arteriosclerosis, hypertension, diabetes mellitus, obesity.

Aged↗
PubMed1991

Rupture of the internal elastic lamina and vascular fragility in stroke-prone spontaneously hypertensive rats.

We studied a possible relation between stroke and an enhanced susceptibility to rupture of the arterial internal elastic lamina by comparing stroke-prone spontaneously hypertensive rats with spontaneously hypertensive rats, which have a very low incidence of stroke. We quantified interruptions in the internal elastic lamina in certain arteries and studied the effect of beta-aminopropionitrile, an inhibitor of cross-link formation in collagen and elastic fibers, on rupture of the internal elastic lamina and on mortality in these two substrains. To eliminate any influence of higher blood pressure in the stroke-prone rats on the parameters studied, we used antihypertensive treatment to obtain equivalent blood pressures in the two substrains. Results showed that stroke sensitivity was associated with an enhanced early spontaneous rupture of the internal elastic lamina in the caudal artery, an increased susceptibility to beta-aminopropionitrile-induced rupture of the internal elastic lamina, and earlier mortality, mainly from aortic rupture, under beta-aminopropionitrile treatment. These findings suggest that stroke-prone rats have an enhanced minor connective tissue defect that is expressed by rupture of the internal elastic lamina and may be related, at least in part, to their greater vascular fragility and increased susceptibility to stroke.

Animals↗