Atrial natriuretic peptide modulates the effect of angiotensin II on the concentration of free calcium in the cytosol of Mandin-Darby canine kidney cells.
The effect of angiotensin II (ANG II) and atrial natriuretic peptide (ANP) on intracellular free calcium concentration [Ca2+]i was investigated in Mandin-Darby canine kidney (MDCK) cells in culture. Changes in [Ca2+]i were monitored fluorometrically with the Ca(2+)-sensitive probe fura-2/AM at 37 degrees C using a Perkin-Elmer LS-5 spectrofluorimeter (excitation 340/380 nm, slit 3 nm; emission 520 nm, slit 10 nm). MDCK cells exhibited a mean baseline [Ca2+]i of 98 +/- 10 nM. The addition of increasing concentrations of ANG II (1 pM to 1 microM) to the cell suspension led to a progressive increase in [Ca2+]i to 2-3 times basal levels. In contrast, addition of 1 microM ANP to the cell suspension led to a very rapid 60% decrease in [Ca2+]i. The addition of 1 pM to 1 microM ANG II immediately after 1 microM ANP caused an increase in [Ca2+]i which never exceeded the basal level in the absence of ANP. The data indicate that ANG II increases cell [Ca2+]i, as expected, and provide the new observation that ANP reduces [Ca2+]i in these cells. Furthermore, ANP reduces the increase in [Ca2+]i elicited by ANG II, thus modulating the effect of ANG II on [Ca2+]i.
Nascimento-Gomes
G
G
Departamento de Fisiologia, Escola Paulista de Medicina, São Paulo, Brasil.
Souza
M O
MO
Vecchia
M G
MG
Oshiro
M E
ME
Ferreira
A T
AT
Mello-Aires
M
M
D000704:Analysis of Variance; D000804:Angiotensin II / Q000378:metabolism / Q000494:pharmacology*; D000818:Animals; D009320:Atrial Natriuretic Factor / Q000378:metabolism / Q000494:pharmacology*; D002118:Calcium / Q000378:metabolism*; D000242:Cyclic AMP / Q000378:metabolism; D003600:Cytosol / Q000378:metabolism*; D004285:Dogs; D007668:Kidney / Q000166:cytology*; D011945:Receptors, Angiotensin / Q000378:metabolism; D013050:Spectrometry, Fluorescence
D011945:Receptors, Angiotensin; D000804:Angiotensin II; D009320:Atrial Natriuretic Factor; D000242:Cyclic AMP; D002118:Calcium