Transport of beta-blockers and calcium antagonists by diffusion in cat myocardium
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Transport of beta-blockers and calcium antagonists by diffusion in cat myocardium. / Haunsø, Stig; Sejrsen, Per; Svendsen, Jesper Hastrup.
I: Journal of Cardiovascular Pharmacology, Bind 17, Nr. 3, 01.03.1991, s. 357-64.Publikation: Bidrag til tidsskrift › Tidsskriftartikel › Forskning › fagfællebedømt
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T1 - Transport of beta-blockers and calcium antagonists by diffusion in cat myocardium
AU - Haunsø, Stig
AU - Sejrsen, Per
AU - Svendsen, Jesper Hastrup
PY - 1991/3/1
Y1 - 1991/3/1
N2 - Beta-blockers and calcium antagonists have been claimed to possess cardioprotective properties. This study addresses the question of whether a significant amount of these drugs will reach the cardiac myocytes during no-flow ischemia, where solute transport depends solely on diffusion. In anesthetized cats the hearts were excised. Apparent diffusion coefficients in cat myocardium at 37 degrees C (D'37) for 14C-verapamil (protein bound), 3H-metoprolol (lipophilic), 3H-atenolol (hydrophilic), and 3H-propranolol (lipophilic and protein bound) were determined by means of a "true transient diffusion" method and compared with the free diffusion coefficients in water (D37). D'37 of 14C-verapamil, 3H-metoprolol, 3H-atenolol, and 3H-propranolol (in cm2 s-1 10(5)) were (mean +/- SEM) 0.025 +/- 0.002, 0.055 +/- 0.003, 0.041 +/- 0.007, and 0.025 +/- 0.002, respectively. The mean diffusive progression of the concentration profile of 3H-metoprolol and 3H-atenolol into the tissue during 20 min was calculated to be 0.36 and 0.31 mm, respectively. The protein binding of 14C-verapamil and 3H-propranolol caused a significant fall in the progression to 0.24 mm for both drugs. These results indicate that, by diffusion, these drugs traverse the tissue too slowly to reach a significant amount of myocardium before myocyte necrosis occurs during conditions of noflow. Cardioprotective drugs are probably most effective, provided sufficient amounts are present in the tissue prior to the ischemic episode or sufficient supply via collateral blood flow is achieved.
AB - Beta-blockers and calcium antagonists have been claimed to possess cardioprotective properties. This study addresses the question of whether a significant amount of these drugs will reach the cardiac myocytes during no-flow ischemia, where solute transport depends solely on diffusion. In anesthetized cats the hearts were excised. Apparent diffusion coefficients in cat myocardium at 37 degrees C (D'37) for 14C-verapamil (protein bound), 3H-metoprolol (lipophilic), 3H-atenolol (hydrophilic), and 3H-propranolol (lipophilic and protein bound) were determined by means of a "true transient diffusion" method and compared with the free diffusion coefficients in water (D37). D'37 of 14C-verapamil, 3H-metoprolol, 3H-atenolol, and 3H-propranolol (in cm2 s-1 10(5)) were (mean +/- SEM) 0.025 +/- 0.002, 0.055 +/- 0.003, 0.041 +/- 0.007, and 0.025 +/- 0.002, respectively. The mean diffusive progression of the concentration profile of 3H-metoprolol and 3H-atenolol into the tissue during 20 min was calculated to be 0.36 and 0.31 mm, respectively. The protein binding of 14C-verapamil and 3H-propranolol caused a significant fall in the progression to 0.24 mm for both drugs. These results indicate that, by diffusion, these drugs traverse the tissue too slowly to reach a significant amount of myocardium before myocyte necrosis occurs during conditions of noflow. Cardioprotective drugs are probably most effective, provided sufficient amounts are present in the tissue prior to the ischemic episode or sufficient supply via collateral blood flow is achieved.
KW - Adrenergic beta-Antagonists
KW - Animals
KW - Atenolol
KW - Biological Transport
KW - Calcium Channel Blockers
KW - Cats
KW - Diffusion
KW - Metoprolol
KW - Myocardium
KW - Propranolol
KW - Sucrose
KW - Verapamil
M3 - Journal article
C2 - 1711595
VL - 17
SP - 357
EP - 364
JO - Journal of Cardiovascular Pharmacology
JF - Journal of Cardiovascular Pharmacology
SN - 0160-2446
IS - 3
ER -
ID: 299501