Search Results

You are looking at 1 - 2 of 2 items for

  • Author: Y. S. Davidson x
  • Refine by access: All content x
Clear All Modify Search
Y. S. Davidson
Search for other papers by Y. S. Davidson in
Google Scholar
PubMed
Close
,
I. Davies
Search for other papers by I. Davies in
Google Scholar
PubMed
Close
, and
C. Goddard
Search for other papers by C. Goddard in
Google Scholar
PubMed
Close

ABSTRACT

The mechanism of water conservation is impaired in ageing mammals. An age-related defect in the release of vasopressin has been implicated but, more recently, attention has moved to the renal component of the water conservation mechanism. Previous studies using renal cells prepared from mice of different ages have shown that the threshold dose of vasopressin required to elicit a significant rise in cyclic AMP (cAMP) was greater in older animals. The dose–response curve was moved to the right in 35-month-old mice, i.e. the concentration of vasopressin required to give maximum cAMP output was increased. To investigate this further we examined the binding of vasopressin to renal medullary cells maintained in short-term culture, to determine whether the decreased response of cAMP levels to vasopressin is due to changes in hormone-receptor interaction. In 6-month-old male mice the dissociation constant (K d) was 2·38 nmol/l and the maximum binding of the hormone (Bmax) was 47·6 fmol/106 cells, and at 30 months of age K d was 2·37 nmol/l and Bmax was 47·0 fmol/106 cells. In female mice the changes were more complicated because the data for the 6-month-old mice could be split into two groups. It is concluded that there are no age-related differences in the numbers of receptors or their affinity for vasopressin, and that the decreased cAMP response is probably associated with post-receptor mechanisms in this species.

J. Endocr. (1987) 115, 379–385

Restricted access
C. Goddard
Search for other papers by C. Goddard in
Google Scholar
PubMed
Close
,
Y. S. Davidson
Search for other papers by Y. S. Davidson in
Google Scholar
PubMed
Close
,
B. B. Moser
Search for other papers by B. B. Moser in
Google Scholar
PubMed
Close
,
I. Davies
Search for other papers by I. Davies in
Google Scholar
PubMed
Close
, and
E. B. Faragher
Search for other papers by E. B. Faragher in
Google Scholar
PubMed
Close

ABSTRACT

The effect of age on the cyclic AMP (cAMP) response to increases in the concentration of arginine vasopressin in the presence of isobutyl methylxanthine (100 μmol/l) was studied in an in-vitro renal cell suspension prepared from C57BL/Icrfat mice at 6, 12, 18, 24, 29 and 35 months of age. Comparison of the response of the preparation to vasopressin, calcitonin and parathyroid hormone suggested that it was enriched with renal medullary cells. Basal cAMP output was similar throughout but the threshold dose of vasopressin increased from 1 × 10−11 mol/l (6, 12 and 18 months of age) to 1 × 10−10 mol/l (24, 29 and 35 months of age). The dose–response curve in 35-month-old mice was shifted to the right with the concentration of vasopressin required to give half maximal cAMP increased from 9·4 ± 0·37 × 10−11 mol/l (6 months) to 3·5±1·6 × 10−10 mol/l (35 months). Maximum cAMP output at 1 × 10 −9 mol/l was also reduced in the same animals (stimulated:basal ratio, 51·22±19·12 at 6 months; 11·50 ± 6·02 at 35 months). The results suggest that the lack of renal response to vasopressin in terms of cAMP metabolism may play a role in the well-documented age-related decline in urine-concentrating ability in experimental animals and elderly people.

J. Endocr. (1984) 103, 133–139

Restricted access