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Front‐surface fluorometry with fura‐2 and effects of nitroglycerin on cytosolic calcium concentrations and on tension in the coronary artery of the pig
Author(s) -
Abe Shimako,
Kanaide Hideo,
Nakamura Motoomi
Publication year - 1990
Publication title -
british journal of pharmacology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.432
H-Index - 211
eISSN - 1476-5381
pISSN - 0007-1188
DOI - 10.1111/j.1476-5381.1990.tb14118.x
Subject(s) - calcium , fura 2 , cytosol , nitroglycerin (drug) , chemistry , biophysics , medicine , biochemistry , anesthesia , biology , enzyme
1 By use of front‐surface fluorometry and fura‐2‐loaded strips of the coronary artery of the pig, the effects of nitroglycerin (NG) on cytosolic Ca 2+ concentrations ([Ca 2+ ] i ) and on tension development were measured simultaneously. 2 Both high K + depolarization and histamine increased [Ca 2+ ] i and tension in a concentration‐dependent manner. However, the tension development in relation to the [Ca 2+ ] i increase ([Ca 2+ ] i ‐tension relation) observed with histamine was much greater than that observed with K + depolarization. 3 NG reduced in a concentration‐dependent manner both [Ca 2+ ] i and tension, irrespective of whether the vascular strips were in a resting state or during exposure to high K + or to histamine stimulation. However, the extent of reduction in tension (relaxation) was greater than that expected from the reduction in [Ca 2+ ] i based on the [Ca 2+ ] i ‐tension relationship observed with K + ‐depolarization. 4 In the absence of extracellular Ca 2+ , NG depleted stored Ca 2+ and also inhibited Ca 2+ release from histamine‐sensitive stores, but had no effect on the caffeine‐sensitive stores. NG inhibited the caffeine‐induced tension development with no change in [Ca 2+ ] i . 5 We suggest that NG relaxes the coronary artery of the pig by reducing [Ca 2+ ] i and also by directly controlling contractile elements through second messengers not related to changes in [Ca 2+ ] i .