By Daphne Walet and Tashi Gillett-Skeath
noradrenaline
intracellular calcium
IP
cAMP and ATP
Results
bradykinin and neurotensin
bradykinin had the same pathway
cells treated simultaneously had the same response
bradykinin and neurotensin were able to desensatise one another
neurotensin was antagonised by bradykinin receptor antagonists. It was better antagonised by the B2 specific HOE140.
able to displace one another
Neurotensin analogues were also tested. Only one which conserved the C terminal region had any effect
is that neurotensin therefore activates the
B2 bradykinin receptor
Thank you for your attention!
We would be happy to answer any questions
from the evidence given...
we would agree with the conclusions drawn BUT we are unsure of the quality of data given.
We feel that...
- The organisation of the paper was poor
- Some data was mentioned but excluded
- Methods were not laid out in a repeatable manner
- No experimental aims
- No further studies
- Controls not mentioned
Conclusion
Neurotensin
- Neuropeptide
- A variety of effects:
- increased pain tolerance
- dopamine transmission
- anterior pituatory hormone secretion
- GI tract
- Cardiovascular system
- growth promotion
- hypothermia
- believed to have specific receptors
Why the experiments were carried out
there is some evidence of further neurotensin binding sites:
- SR48692 to antagonises previously identified specific receptors.
- SR48692 does not antagonise some of the effects of neurortensin.
- Some physiological effects occur at concentrations much higher than would be expected.
Activation of B2 bradykinin receptors by neurotensin
presentation on a paper by Tae-Ju Park, Kyong-Tai Kim.
Cellular Signalling
secretion was tested using radio-isotopes and a scintilation counter
Methods
Several relatively small scale experiments were used.
measured using sulfinpyrazone
time not strictly controlled
these were carried out using PC12 cells.
3
good method for quantification?
purified using chromatography
lost product?
measured specific and non-specific binding
repeatable method?
response to neurotensin was also found in other bradykinin receptor expressing cells in other species.
- Norepinephrine and intracellular calcium were increased at neurotensin concentrations of 1-500 M and 10-500 M respectively with the maximal increase at 500.
- Lower affinity than displayed by specific receptors.
- IP was also found to increase and assumed to be the trigger of intracellular calcium release.
- Pre-treatment of cells with thapsogargin showed that calcium was derrived from thapsogargin stores.
- cAMP levels were now also tested as there is proven involvement with neurotensin specific receptors
- These results led to tests to see if the bradykinin receptore were involved.