Calcium, phosphoinositide, and 1,2-diacylglycerol responses of blood vessels of deoxycorticosterone acetate-salt hypertensive rats to endothelin-1.
In previous studies a decreased responsiveness to endothelin-1 (ET-1) of conduit arteries and resistance vessels of deoxycorticosterone acetate (DOCA)-salt hypertensive rats was found in comparison with uninephrectomized controls. Decreased isometric force, number of receptors, and inositol phosphate accumulation were reported in the DOCA-salt animals. In the present study effects of ET-1 on cytosolic free calcium, inositol phosphates, and 1,2-diacylglycerol were investigated in blood vessels of DOCA-salt hypertensive rats. Basal cytosolic free calcium, measured with the fluorescent dye fura-2, was 201 +/- 41 nmol/l in mesenteric arteries of DOCA-salt rats and 45 +/- 9 nmol/l in uninephrectomized controls (p less than 0.01). The maximal response of cytosolic free calcium (to 30 nmol/l ET-1) was 176 +/- 22% of the basal value for DOCA-salt and 242 +/- 6% for uninephrectomized rats (p less than 0.05). The concentration giving 50% of the maximum response was 9.0 and 6.5 nmol/l for DOCA-salt rats and controls, respectively. Inositol phosphate production after stimulation with 100 nmol/l ET-1 in the presence of LiCl was lower by at least 30% (p less than 0.01) in both aorta and mesenteric arteries of DOCA-salt hypertensive versus control rats. Basal levels of diacylglycerol in aorta were similar in DOCA-salt rats and in controls and did not respond to a 100 nmol/l ET-1 stimulation in the DOCA-salt rats, in contrast to the increase found in the control uninephrectomized rats (p less than 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)
Flückiger
J P
JP
Experimental Hypertension Laboratory, University of Montreal, Quebec, Canada.
Nguyen
P V
PV
Li
G
G
Yang
X P
XP
Schiffrin
E L
EL
D000818:Animals; D001808:Blood Vessels / Q000378:metabolism*; D002118:Calcium / Q000378:metabolism*; D003900:Desoxycorticosterone; D004075:Diglycerides / Q000378:metabolism*; D006973:Hypertension / Q000139:chemically induced / Q000378:metabolism*; D007295:Inositol Phosphates / Q000378:metabolism; D007425:Intracellular Membranes / Q000378:metabolism; D008297:Male; D008638:Mesenteric Arteries / Q000378:metabolism; D009994:Osmolar Concentration; D010716:Phosphatidylinositols / Q000378:metabolism*; D051381:Rats; D011919:Rats, Inbred Strains
C011439:1,2-diacylglycerol; D004075:Diglycerides; D007295:Inositol Phosphates; D010716:Phosphatidylinositols; D003900:Desoxycorticosterone; D002118:Calcium