These tools will no longer be maintained as of December 31, 2024. Archived website can be found here. PubMed4Hh GitHub repository can be found here. Contact NLM Customer Service if you have questions.


Pubmed for Handhelds

PUBMED FOR HANDHELDS

Search MEDLINE/PubMed

  • Title: The effects of dipyridamole and theophylline on rat pial vessels during hypocarbia.
    Author: Ibayashi S, Ngai AC, Meno JR, Winn HR.
    Journal: J Cereb Blood Flow Metab; 1988 Dec; 8(6):829-33. PubMed ID: 3142892.
    Abstract:
    Hypocarbia results in an increase in brain adenosine concentrations, presumably because of brain hypoxia associated with hypocarbic vasoconstriction. It was hypothesized that adenosine limits the degree of hypocarbic vasoconstriction. To test this hypothesis, the effects of dipyridamole and theophylline on CO2 reactivity during hypocarbia were investigated in anesthetized rats. Dipyridamole should reduce the vasoconstriction by potentiating adenosine action, whereas theophylline should increase the vasoconstriction by blocking adenosine receptors. Cortical pial arterioles of mechanically ventilated and anesthetized rats were displayed on a video monitor system through a closed cranial window. Arterial blood pressure and oxygen tension were stable. CO2 reactivity, formulated as 100 X [delta diameter (micron)/resting diameter (micron)]/delta PaCO2 (mmHg), in the hypocarbic phase was calculated before and after topical superfusion of dipyridamole (10(-6) M; n = 7) and theophylline (5 X 10(-5) M; n = 6). CO2 reactivity was significantly decreased after superfusion of dipyridamole (0.57 +/- 0.08; mean +/- SEM) as compared with mock cerebrospinal fluid (CSF) (0.97 +/- 0.17, p less than 0.05, n = 7). On the other hand, CO2 reactivity after superfusion of theophylline was increased (1.63 +/- 0.28) as compared with mock CSF (1.00 +/- 0.20, p less than 0.05, n = 6), indicating that adenosine is involved in hypocarbic vasoconstriction.
    [Abstract] [Full Text] [Related] [New Search]