Blood Vessels 2

Question 1

why is NPY preferentially release by high freq stim: Ca influx via ___ is ___?

Answer 1

Ca influx via N type Ca channels is localized; buffereing prevents diffusion in cytoplasm

Question 2

NA release vs NPY release: Ca levels needed?

Answer 2

NA vesicles need high Ca for release, NPY vesicles sensitive to small increases in Ca

Question 3

why is NPY preferentially release by high freq stim: location of vesicles?

Answer 3

high freq stimulation Ca influx overcomes buffering capacity of cytoplasm and reaches NPN vesicles that tend to be away from release sites. (NA closer)

Question 4

kidney: renal nerves contain what NT? effect?

Answer 4

DA: renal vasodilation, increases glomerular filtration rate, sodium excretion

Question 5

parasympathetic vasodilation in cerebral/cephalic arteries: what two NTs?

Answer 5

ACh and VIP.

Question 6

cerebral vessel constriction via?

Answer 6

5HT innervation of cerebral vessels; powerful vasoconstrictor

Question 7

cardiovacular response to IV adrenaline? due to what?

Answer 7

systolic + diastolic BP increase: due to alpha vasoconstrictor effect + B1 stimulation of heart

Question 8

cardiovascular response as adrenaline falls? due to?

Answer 8

characteristic late fall in diastolic + mean BP: beta 2 effect on blood vessels

Question 9

IV adrenaline: skeletal muscle? due to?

Answer 9

lots of b2 receptors = blood flow increases (B2 = relaxation aka vasodilation)

Question 10

cellular mech. of a1 adrenergic effect: transduction mech?

Answer 10

a1 adrenergics: PLC = IP3 and DAG. IP3 causes increase in calcium, activates calmodulin, then MLCK (myosin light chain kinase)

Question 11

once MLCK is activate what happens?

Answer 11

myosin light chain kinase + ATP = myosin is phosphorylated. now can interact with actin = contraction

Question 12

cellular mech of b2 adrenergic effects (transduction pathway)?

Answer 12

B2 adrenergic = increased cAMP = PKA. PKA inhibits MLCK. end result is vasodilation

Question 13

cAMP effect on vascular smooth muscle

Answer 13

RELAXATION (B2 adrenergicsL cAMP inhibits MLCK)

Question 14

receptors for ACh on blood vessels? but? so dependent on?

Answer 14

receptors for ACh present on endothelial cells of blood vessels, but no parasympathetic cholinergic innervation = endothelium dependent relaxation of blood vessels

Question 15

mAChR and blood vessels: mechanism?

Answer 15

activation of NOS, release of NO, interacts with guanylyl cyclase = vascular smooth muscle relxation

Question 16

endothelium dependent relaxation mediated by what substances? (3) not?

Answer 16

not ACh. mediators like substance P, 5HT and bradykinin increase NO.

Question 17

NO: transduction mechanism?

Answer 17

increases cGMP = protein kinase G. inhibits MLCK = relaxation.