Premium
Vascular effects of parathyroid hormone and parathyroid hormone‐related protein in the split hydronephrotic rat kidney.
Author(s) -
Endlich K,
Massfelder T,
Helwig J J,
Steinhausen M
Publication year - 1995
Publication title -
the journal of physiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.802
H-Index - 240
eISSN - 1469-7793
pISSN - 0022-3751
DOI - 10.1113/jphysiol.1995.sp020599
Subject(s) - afferent arterioles , endocrinology , medicine , parathyroid hormone , chemistry , macula densa , vasodilation , angiotensin ii , kidney , renin–angiotensin system , receptor , calcium , blood pressure
1. The effects of locally applied parathyroid hormone‐related protein (PTHRP), a putative autocrine/paracrine hormone, on vascular diameters and glomerular blood flow (GBF) in the split hydronephrotic rat kidney were studied. As PTHRP interacts with parathyroid hormone (PTH) receptors in all tissues tested so far, the effects of PTHRP were compared with those of PTH. 2. Preglomerular vessels dilated in a concentration‐ and time‐dependent manner that was almost identical for PTH and PTHRP. A significant preglomerular vasodilation (5‐17%) occurred at a threshold concentration of 10(‐10) mol l‐1 PTH or PTHRP, which raised GBF by 20 +/‐ 2 and 31 +/‐ 4%, respectively (means +/‐ S.E.M., n = 6). PTH or PTHRP (10(‐7) mol l‐1) increased preglomerular diameters (11‐36%) and GBF (60 +/‐ 10 and 70 +/‐ 8%, respectively) to near maximum. The most prominent dilatation was located at the interlobular artery and at the proximal afferent arteriole. 3. Efferent arterioles were not affected by either PTH or PTHRP. 4. Estimated concentrations of half‐maximal response (EC50) for preglomerular vasodilatation and GBF increase were in the nanomolar to subnanomolar range. 5. After inhibition of angiotensin I‐converting enzyme by 2 x 10(‐6) mol kg‐1 quinapril I.V. (n = 6), 10(‐8) mol l‐1 PTHRP dilated preglomerular vessels and efferent arterioles (9 +/‐ 1% proximal and 6 +/‐ 1% distal). 6. We conclude that the renal vasculature of the hydronephrotic kidney is highly sensitive to vasodilatation by PTH and PTHRP, which, in addition, may constrict efferent arterioles by stimulating renin release.(ABSTRACT TRUNCATED AT 250 WORDS)