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Nucleotide coronary vasodilation in guinea pig hearts
Mark W Gorman1, Kayoko Ogimoto, Margaret V Savage
1Department of Physiology and Biophysics, University of Washington School of Medicine, Box 357290, Seattle, WA 98195-7290, USA. mgorman@u.washington.edu
Summary
Adenine nucleotides like ATP and ADP trigger coronary vasodilation through P1 and P2Y1 receptors in guinea pig hearts. P1 receptors primarily mediate responses to AMP, while P2Y1 receptors are key for ADP-induced vasodilation.
Area of Science:
- Cardiovascular Physiology
- Pharmacology
- Receptor Biology
Background:
- Adenine nucleotides play a crucial role in regulating coronary blood flow.
- Purinergic signaling, involving P1 and P2 receptors, is essential for cardiovascular homeostasis.
- Understanding the specific roles of P1 and P2Y1 receptors in coronary vasodilation is vital for therapeutic development.
Purpose of the Study:
- To investigate the distinct roles of P1 and P2Y1 receptors in mediating coronary vasodilator responses to adenine nucleotides (adenosine, AMP, ADP, ATP).
- To differentiate the contribution of each receptor type to the vasodilation induced by various adenine nucleotides in isolated guinea pig hearts.
Main Methods:
- Isolated guinea pig heart perfusion model at constant pressure.
- Bolus arterial injections of adenine nucleotides.
- Measurement of peak coronary blood flow increase.
- Pharmacological blockade of P1 and P2Y1 receptors using specific antagonists (8-(p-sulfophenyl)theophylline and MRS 2179) and adenosine deaminase.
Main Results:
- Adenosine-induced vasodilation was inhibited by P1 receptor blockade and adenosine deaminase.
- AMP-induced vasodilation was solely mediated by P1 receptors.
- ADP-induced vasodilation involved both P1 and P2Y1 receptors, with a predominant role for P2Y1.
- ATP-induced vasodilation was primarily mediated by P1 receptors (via AMP), with a minor contribution from P2Y1 receptors.
Conclusions:
- In guinea pig coronary circulation, ATP-induced vasodilation is mainly due to AMP acting on P1 receptors, with a smaller contribution from ATP/ADP on P2Y1 receptors.
- ADP-induced vasodilation is largely mediated by P2Y1 receptors, with a minor P1 receptor contribution.
- AMP responses are exclusively mediated by P1 receptors, and adenosine has a minimal role in nucleotide-induced vasodilation.