The effect of atrial natriuretic peptide on cytosolic free calcium in cultured vascular smooth muscle cells.
Effect of atrial natriuretic peptide (ANP) on cytosolic free calcium [( Ca2+]i) was studied in monolayers of cultured vascular smooth muscle (VSM) cells loaded with a fluorescent calcium indicator, fura-2. Vasoconstrictive hormones, angiotensin II (AII) and Arg8-vasopressin (AVP) induced initial rapid rises in [Ca2+]i, followed by sustained elevation of [Ca2+]i. ANP (Atriopeptin III 10(-8) M) decreased both the resting level and the sustained elevation of [Ca2+] i induced by AII and AVP. ANP also decreased the rise in [Ca2+]i induced by high potassium (K+) depolarization. AVP-induced initial rapid rise in [Ca2+]i was not inhibited by ANP in the presence or absence of the phosphodiesterase inhibitor, isobutylmethylxanthine 0.1 mM, which has been shown to fully enhance ANP-induced cyclic GMP accumulation. On the other hand, a calcium antagonist, nicardipine, inhibited the high K+-induced rise in [Ca2+]i, whereas it had no effect on not only initial but also sustained rises in [Ca2+]i induced by AVP or AII. These results suggest that ANP has an ability to decrease [Ca2+]i not through inhibition of voltage-sensitive calcium channels, and that neither ANP nor ANP-induced cyclic GMP may affect initial hormone-induced rise in [Ca2+]i. In conclusion, an ability to decrease [Ca2+]i is implicated in ANP-induced relaxation of VSM.
Takeuchi
K
K
Second Department of Internal Medicine, Tohoku University School of Medicine, Sendai, Japan.
Abe
K
K
Yasujima
M
M
Sato
M
M
Kanazawa
M
M
Yoshinaga
K
K
D015056:1-Methyl-3-isobutylxanthine / Q000494:pharmacology; D000804:Angiotensin II / Q000494:pharmacology; D000818:Animals; D001127:Arginine Vasopressin / Q000494:pharmacology; D009320:Atrial Natriuretic Factor / Q000494:pharmacology*; D002118:Calcium / Q000378:metabolism*; D002478:Cells, Cultured; D003600:Cytosol / Q000187:drug effects / Q000378:metabolism; D004533:Egtazic Acid / Q000494:pharmacology; D004987:Ethers / Q000494:pharmacology; D015759:Ionomycin; D007700:Kinetics; D008297:Male; D008638:Mesenteric Arteries / Q000187:drug effects / Q000378:metabolism; D009131:Muscle, Smooth, Vascular / Q000187:drug effects / Q000378:metabolism*; D009529:Nicardipine / Q000494:pharmacology; D011189:Potassium Chloride / Q000494:pharmacology; D051381:Rats; D011919:Rats, Inbred Strains
D004987:Ethers; D000804:Angiotensin II; D001127:Arginine Vasopressin; D004533:Egtazic Acid; D015759:Ionomycin; D011189:Potassium Chloride; D009320:Atrial Natriuretic Factor; D009529:Nicardipine; D002118:Calcium; D015056:1-Methyl-3-isobutylxanthine