Imaging receptors within the vascular wall

Question 1

Fluorescence for studying receptors

Answer 1

Detection of NA in tissues.
Antibodies to receptors - not particularyselective, mostly done on dead tissue so does not show receptor motility.
GFP tagged receptors - can make calles express receptors with this attached, they are recombinant receptors however so not always related to the cell.
Fluorescent peptides and ligands can be created.
Fl-prazosin - no longer confers prazosin specificity but still a useful drug for fluorotagging.

Question 2

Validation of a fluorescent ligand

Answer 2

Treat as any new drug or experimental compound.
Ligand binding studies.
Biochemical assays.
Functional tests on whole tissues.
Important to check affinity of any new compound.

Question 3

Competative fluorodrugs

Answer 3

When a tissue shows high fluorescence when the drug alone is acting on it, but low fluorescence when other drugs are acting present, the fluorodrug must be competative.

Question 4

Receptor clustering

Answer 4

In single cells fluorescence is diffuse but clustered, as receptors are activated by agonist they cluster, forming vesicles, and internalise into the cell.

Question 5

Alpha1 receptors

Answer 5

Show on endothelial cells, trapped inside the interstitial elastic lamenna, unsure of subtype.

Question 6

Beta receptors

Answer 6

Present in human endothelial cells.
Lots of beta receptors present on nerves between fat cells in the adventitia. Must mean NA is present to stimulate them, possible auto feedback mechanism. Blood vessels that run through fat might also have NA in plasma.
Lots of beta receptors present at branch points in small arteries, possibly to keep vesels open and to facilitate flow.
Two populations of advantitial cell, one with alpha1 receptors one without.

Question 7

ET1

Answer 7

Highly potent vasoconstrictor
Made in endothelium
Receptors on nerves and advantitial cells.
Possibly released into circulation.

Question 8

Fat and vascular function

Answer 8

Branches of nerves run through fat

B receptors in fat stimulated by NA

Question 9

GPR55

Answer 9

Present in smooth muscle and fat
Blocking this may be a good anti-obesity drug.

Highly expressed in smooth muscle layers of prostate in prostate cancer.