The authors have studied the ability of prostacyclin to reverse contractions of human basilar arteries in vitro that were induced by a wide range of substances implicated in the etiology of cerebral arterial spasm. Prostacyclin (10(-10) to 10(-6)M) caused a dose-related reversal of contractions induced by 5-hydroxytryptamine, noradrenaline, angiotensin II, prostaglandin (PG)F2 alpha, and U-46619 (a thromboxane-A2 mimetic). These agents were tested at concentrations or volumes that produced almost maximum or maximum responses and those that produced approximately 50% of the maximum response. Contractions induced by maximum concentrations of angiotensin II and U-46619 were least affected by prostacyclin. In addition, contractions induced by thromboxane-A2 generated from guinea-pig lung were reversed in a dose-dependent fashion by prostacyclin. This ability of prostacyclin to physiologically antagonize contractions of the human basilar artery in vitro induced by high concentrations of various spasmogenic agents suggests that such a potent vasodilator agent or more stable analogue may be of value in the treatment of such disorders as cerebral arterial spasm following subarachnoid hemorrhage.
Experiments were performed to determine the effects of fibrin-fibrinogen degradation products on the human basilar artery in vivo. Citrated plasma and streptokinase were incubated at 37 degrees C to produce a preparation of fibrinogen degradation products. Aliquots of the incubate were obtained at 90 minutes, 48 hours, and 1 and 2 weeks after preparation, and were separated into fractions of different molecular weight (MWt), using an ultrafiltration technique. Each fraction was tested at each of the above times for contractile activity and possible interaction with a threshold concentration of 5-hydroxytryptamine (5-HT) on the human basilar artery. Contractile activity was initially confined to the 90-minute aliquot fraction MWt greater than 100,000, but as the incubation proceeded, such activity was also seen in the lower MWt fraction less than 100,000 greater than 10,000 at all time intervals. This activity was never seen in the fraction MWt less than 10,000 at any time. Enhancement of the 5-HT response was initially confined to the higher molecular weight fractions, but after 48-hour incubation all fractions showed this activity. It is suggested that products of fibrin-fibrinogen degradation may be involved directly or indirectly in influencing the pathophysiological mechanism(s) responsible for cerebral arterial spasm following subarachnoid hemorrhage.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.