Pharmacology with Autonomic Nervous System- 8

Question 1

Pharmacology

Answer 1

the study of the histories, sources, chemical properties, biological actions, biological handling and therapeutic uses of drugs in living organisms.

Question 2

Autonomic nervous system

Answer 2

maintains homeostasis of visceral tissues. Primarily regulates the functions of 3 primary cell types- smooth muscle, cardiac muscle, and secretory glands. Provides a means for the body to alter the functions of many tissues in response to external (5 senses) or internal (body temp, pain, BP, fear, disease) changes.

Question 3

Uses of autonomic drugs

Answer 3

re-establish normal function in dysfunctional organs.
Cardiovascular imbalances, GI disturbances, Respiratory-pulmonary disorders, urinary tract disorders, miscellaneous. Offset visceral changes secondary to CNS disorders or treatments with CNS acting drugs. Treat poisoning and hypersensitivity reactions.

Question 4

Autonomic reflexes

Answer 4

common response to a primary drug-evoked change in a visceral organ. Ex: phenylphrine- contracts vascular smooth muscle, increased peripheral resistance, activates baroreceptors.
Reflexes involve higher level “integration centers” that are present at distinct loci.

Question 5

sites of drug action in the ANS

Answer 5

pic pg. 4

Question 6

Autonomic ganglia

Answer 6

all ganglia (sympathetic and parasympathetic) use identical forms of chemical transmission. Ganglionic drugs produce pervasive wide-spread effects. Unintentional site of action for some drugs (anti-AChE, muscle relaxants). Acetylcholine from preganglionic neuron stimulates nicotinic receptors on postganlionic neurons- ganglionic blockers are nicotinic cholinergic antagonists. Secondary events have no proven function.

Question 7

Neuroeffector junction

Answer 7

primarily intended site of action for ANS drugs. Nearly all visceral tissues receive dual innervation by sympathetic and parasympathetic neurons. Elicit opposite tissue/organ responses.

Question 8

Pharmacological antagonism

Answer 8

blockade of an agonist by an antagonist.

Ex: phancuronium blockade of ACh at skeletal muscles nicotinic receptors

Question 9

Physiological antagonism

Answer 9

opposing actions produced by two drugs via actions on different receptors or via distinct mechanisms.
Ex: histamine and epinephrine on bronchial smooth muscle. Histamine causes labored breathing while Epinephrine improves breathing.

Question 10

Physiological antagonism within the autonomic nervous system

Answer 10

allows for different pharmacological approaches for management of numerous disorders. Allows for complimentary treatments that target both branches of the autonomic nervous system.

Question 11

Chemical transmission in the ANS

Answer 11

the sympathetic and parasympathetic branches use different transmitters and receptors for chemical transmissions between postganglionic neurons and target organs. Provides the opportunity for selective intervention with drugs.

Question 12

Sites of drug action at the neuroeffector junction

Answer 12

pic pg. 10

Question 13

Ach synthesis

Answer 13

inhibition is lethal (toxins). Stimulation has unclear effects (lecithin in CNS neurons).

Question 14

Ach release

Answer 14

inhibition can be lethal (botulinum toxin in motor neurons). Stimulation can be lethal (black widow venom in motor neurons).

Question 15

Presynaptic receptors

Answer 15

muscarinic autoreceptors inhibit Ach release. No proven therapeutic relevance.

Question 16

Postsynaptic receptors

Answer 16

represents a major target for therapeutic control of parasympathetic…
Receptors are muscarinic cholinergic receptors (mAChR) .
5 subtypes known, but have unproven therapeutic significance.
Bethanechol, atopine, gyycopyrrolate.

Question 17

Ach elimination

Answer 17

entirely enzymatic (acetylcholinesterase or AChE). No uptake (transport) process. 
Edrophonium, physostigmine, parathion.

Question 18

NE biosynthesis

Answer 18

formed from L-tyrosine via tyrosine hydroxylase. Not a target for therapeutic agents.

Question 19

NE storage and release

Answer 19

storage vesicles can be destroyed and cause prolonged loss of sympathetic activity. Release is enhanced by many compounds.

Question 20

presynaptic receptors

Answer 20

can control transmitter release from nerve terminals. Probably insignificant in autonomic neurons. Important in CNS (xylazine).

Question 21

Postsynaptic receptors

Answer 21

represents a major target for therapeutic control of sympathetic functions. all are classified as adrenergic receptors (alpha and beta). Expression of receptor subtypes is cell specific.

Question 22

NE&EP eliminiation

Answer 22

Eliminated by cellular uptake as well as enzymatic degradation. Uptake- most important elimination process. Enzymatic degradation- mediated by multiple enzymes.

Question 23

mini review

Answer 23

pic pg 12