TY - JOUR
T1 - Prostaglandin influences on afferent arteriolar responses to vasoconstrictor agonists
AU - Inscho, Edward W.
AU - Carmines, Pamela K.
AU - Gabriel Navar, L.
PY - 1990
Y1 - 1990
N2 - The present study was designed to evaluate, at the microvascular level, the ability of prostaglandins E2 (PGE2) and I2 (PGI2) to counteract the afferent vasoconstrictor effects of angiotensin II (ANG II) and norepinephrine (NE). The renal microvasculature of rats pretreated with captopril and indomethacin was studied directly by use of the in vitro blood-perfused juxtamedullary nephron technique combined with videomicroscopy. Afferent arterioles averaged 22.7 ± 0.6 μm ID (n = 59) under control conditions. Topical administration of PGE2 revealed a concentration-dependent afferent vasoconstriction, whereas PGI2 (10-7 to 10-5 M) failed to significantly alter afferent arteriolar diameter. Afferent arterioles constricted during exposure to either 10-9 M ANG II (-15 ± 3%, n = 13) or 10-7 M NE (-19 ± 3%, n = 13). Addition of PGE2 (10-6 M) to the bathing solution enhanced the vasoconstrictor influences of ANG II and NE by an additional 18 ± 6 and 13 ± 4%, respectively. In contrast, while 10-6 M PGI2 had no effect on ANG II-induced afferent vasoconstriction, it did produce a 30% attenuation of NE-induced constriction. Furthermore, pretreatment of the tissue with 10-6 M PGI2 prevented development of NE-induced afferent vasoconstriction. Thus, although local tissue prostanoid concentrations are unknown, it appears that low micromolar concentrations of PGE2 elicit an afferent arteriolar constriction that can accentuate the vascular actions of ANG II and NE on rat juxtamedullary afferent arterioles. In contrast, PGI2 can counteract the vasoconstrictor response to NE, but not ANG II, in this experimental setting.
AB - The present study was designed to evaluate, at the microvascular level, the ability of prostaglandins E2 (PGE2) and I2 (PGI2) to counteract the afferent vasoconstrictor effects of angiotensin II (ANG II) and norepinephrine (NE). The renal microvasculature of rats pretreated with captopril and indomethacin was studied directly by use of the in vitro blood-perfused juxtamedullary nephron technique combined with videomicroscopy. Afferent arterioles averaged 22.7 ± 0.6 μm ID (n = 59) under control conditions. Topical administration of PGE2 revealed a concentration-dependent afferent vasoconstriction, whereas PGI2 (10-7 to 10-5 M) failed to significantly alter afferent arteriolar diameter. Afferent arterioles constricted during exposure to either 10-9 M ANG II (-15 ± 3%, n = 13) or 10-7 M NE (-19 ± 3%, n = 13). Addition of PGE2 (10-6 M) to the bathing solution enhanced the vasoconstrictor influences of ANG II and NE by an additional 18 ± 6 and 13 ± 4%, respectively. In contrast, while 10-6 M PGI2 had no effect on ANG II-induced afferent vasoconstriction, it did produce a 30% attenuation of NE-induced constriction. Furthermore, pretreatment of the tissue with 10-6 M PGI2 prevented development of NE-induced afferent vasoconstriction. Thus, although local tissue prostanoid concentrations are unknown, it appears that low micromolar concentrations of PGE2 elicit an afferent arteriolar constriction that can accentuate the vascular actions of ANG II and NE on rat juxtamedullary afferent arterioles. In contrast, PGI2 can counteract the vasoconstrictor response to NE, but not ANG II, in this experimental setting.
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M3 - Article
C2 - 2115739
AN - SCOPUS:0025100397
SN - 0363-6127
VL - 259
SP - F157-F163
JO - American Journal of Physiology - Renal Fluid and Electrolyte Physiology
JF - American Journal of Physiology - Renal Fluid and Electrolyte Physiology
IS - 1 28-1
ER -