传出神经药物对麻醉兔血压和腺体分泌的影响

Effects of Drugs Affecting the Peripheral Efferent Nervous System on Blood Pressure and Gland Secretion in
Anesthetized Rabbit
XXX
（China Pharmaceutical University，639 Longmian Avenue, Nanjing, Jiangsu, China 210009）
ABSTRACT: OBJECTIVE Observe the effects of drugs affecting the peripheral efferent nervous system on above-mentioned physiological phenomena and comprehend the interaction of this kind of drugs. METHODS Observed the blood pressure by inserting an arterial cannula into the right carotid artery; drugs were injected intravenously into ear margin. RESULTS After the injection of Adr and NA, the blood pressure increased and after the injection of phentolamine, propranolol, pilocarpine and Ach, the blood pressure decreased. CONCLUSION Phentolamine and propranolol can reduce the effect of Adr and NA, cholinergic drugs can lower blood pressure, and atropine can confront this.
KEYWORDS:blood pressure; gland secretion; drugs; the peripheral efferent nervous Introduction
The vegetative nervous system, belonging to the peripheral efferent nervous system, is divided into two subdivisions, the parasympathetic nervous system whose chief transmitter is acetylcholine, and the sympathetic nervous system whose chief transmitter is norepinephrine. The two systems coordinate and oppose each other to maintain normal physiological functions. The drugs affect the parasympathetic and the sympathetic nervous system mainly through the transmitters and receptors. The drug actions can be qualitatively analyzed indirectly through the effects on blood pressure, smooth muscles movement and gland secretion in animals.
Adrenergic drugs: Adr can excite bothα-receptor and β-receptor, shrink the blood vessel and increase the systolic pressure while the diastolic pressure keep unchanged (when the dose is large, diastolic pressure can be increased as the α-receptor is in the ascendant);NA can excite α-receptor mainly, but notβ-receptor, so it can shrink vessel strongly and increase the blood pressure. Isooproterenol can exciteβ-receptor only , increase the shrink force of cardiac muscle and expand the vessel so the diastolic pressure decreased while the systolic pressure increased, in this way the blood pressure gets dropped after all.
Anti-adrenergic drugs: phentolamine is a kind ofα-receptor blockers, it can expand vessel and decrease the blood pressure. Propranolol is a kind of β-receptor blockers, the effects on vessel and blood pressure come from central and periphery two regions, it blocks the β-receptor on the vessel and shrink the blood vessel, increase blood pressure while blocks the β-receptor on central nerve system can expand the vessel and decrease the blood pressure, and it increase the blood pressure after all.
Cholinergic drugs : pilocarpine can excite M-receptor selectively, and express M-function, lead to the secretion increase of grand, especially the sweat gland and salivary glands, and it decrease the force of cardiac muscle so the blood pressure decreased.
M-receptor blockers: artropine can block M-receptors competitively, avoid the combination of M-receptor and Ach, so the secretion reduced and the rhythm of the heart increased.[1]
1 Material and Methods
1.1 Materials
Equipments:
operation table, surgical instruments, physiological pressure detector, flatbed recorder, pressure transducer, syringes, and buret
Reagents:
heparinized saline, normal saline, pentobarbital sodium solution (3%, w/v) Drugs used in this experiment may be found in detail afterward
Animals:
1 rabbit, 2kg male
1.2 Methods
Weigh the rabbit and administer 5g/kg of 20% urethan sodium (iv.) to anesthetize it. Then fix it on the operation table. Cut off the fur on the front of the neck and open the skin along midline. Isolate right carotid artery and insert an arterial cannula filled with heparinized saline and connected to force-displacement transducer linking the physiological pressure detector. After the physiological pressure detector is well regulated, open the artery forceps and then record normal blood pressure.
After surgery, trace a portion of normal blood pressure and intestine movement curve and observe the salivary secretion. Then inject following drugs in turn. After administration every time, infuse 2ml normal saline through infusion tube immediately to make the drug enter the blood circulation entirely. Observe and record the alteration in blood pressure, intestine movement and gland secretion. Don’t give next drug until above-mentioned physiological condition is back to normal or stable level.
A. Observe the effects of adrenergic drugs on blood pressure and salivary secretion.
1) Adrenaline, 10 -4, 10μg/0.1ml/kg
2) Norepinephrine, 10 -4,10μg/0.1ml/kg
B. Observe the effects of α-adrenoceptor blockers on the action of adrenergic drugs.
3) phentolamine, 2.5*10 -2 ,5mg/0.2ml/kg
4) repeat 1)
5) repeat 2)
C. Observe the effects of β-adrenoceptor blockers on the action of adrenergic drugs.
6) propranolol, 10 -3 ,0.1mg/0.1ml/kg
7) repeat 1)
8) repeat 2)
D. Observe the effects of cholinergic drugs on the blood pressure, intestine movement and salivary secretion.
9) pilocarpine, 10 -3 ,0.1mg/0.1ml/kg
10) acetylcholine, 10 -5, 1μg/0.1ml/kg
11) atropine, 5*10 -3 ,0.5mg/0.1ml/kg
12) repeat 13)
13) acetylcholine, 10 -4, 10μg/0.1ml/kg
E Observe the effects of isoprenaline on the blood pressure
2 Results
Fig 1 the effects of adrenergic drugs on blood pressure (normal: 80/100mmHg; after Adr(0.063ml/kg): 100/120mmHg; after NA(0.063ml/kg): 104/124mmHg)
Fig 2 the effects of α-adrenoceptor blockers on the action of adrenergic drugs (after phentolamine(0.063ml/kg): 88/104mmHg→60/88mmHg; after Adr(0.063ml/kg):40/72mmHg →60/92mmHg; after NA(0.063ml/kg): 56/86mmHg→68/100mmHg )
Theoretically, in this section after the injection of Adr, the blood pressure should got dropped as it only can exciteβ-receptor due to the exist of phentolamine blocked theα-receptors.
Fig 3 the effects of β-adrenoceptor blockers on the action of adrenergic drugs (after
propranalol(0.0315ml/kg): 60/80mmHg; after Adr(0.063ml/kg):96/116mmHg; after
NA(0.063ml/kg): 72/96mmHg )
Fig 4 the effects of cholinergic drugs on the blood pressure (after pilocarpine(0.063ml/kg): 64/84mmHg→48/72mmHg; after Ach(0.063ml/kg):36/64mmHg; after atropine(0.0315ml/kg): 54/72mmHg→60/80mmHg; after second Ach(0.063ml/kg): 56/76mmHg; after third
Ach(0.063ml/kg): 68/80mmHg)
After the injection of pilocarpine, the spittle in the mouth of the experiment rabbit was increased and its tongue was moist.
Fig 5 the effects of adrenergic drugs isoprenaline on blood pressure(the blood pressure is
70/80mmHg, and it appeared as arrhymia)
3 Discussions
It is showed that both Adr and NA can make blood pressure increased, as they are α,β-adrenoceptor, they can make blood vessel contract and the force of cardiac muscle strengthened. Phentolamine isα-adrenoceptor blockers, it can block α-adrenreceptor and make blood vessel expand, so the blood pressure descended especially the diastolic pressure, and the action of
adrenergic drugs got smaller, it mainly were systolic pressure got increased. What’s more, the effect of phentolamine on Adr should make it lead to the blood pressure getting down, but in this experiment, we did not get this result. It may be theβ-adrenoceptor on the rabbit’s heart was quite sensitive that the force of the cardiac muscle was too strong and the blood pressure increased. There is another cause that the β-adrenoceptor on the vessel in too insensitive that lead to this result.
Propranolol is β-adrenoceptor blockers this make the force of cardiac muscle weakened and there are some effects of getting blood vessel expanded, all in all, the blood pressure reduced. Adr and NA increased the blood pressure on both diastolic pressure and systolic pressure.
Pilocarpine is a kind of M-receptor agonist, when M-receptor is excited, the force of cardiac muscle decreased and the blood pressure is reduced, and what’s more this also makes the secretion of gland increased and especially the salivary glands. It is similar of the effect of Ach. Atropine can block M-receptor competitively, and reduce the effect of pilocarpine so the blood pressure got increased. Similarly, the concentration of Ach before did not act very apparently as before due to the atropine, but when the concentration got denser, it dropped much more.
Isooproterenol can exciteβ-adrenreceptor only , increase the shrink force of cardiac muscle and expand the vessel so the diastolic pressure decreased while the systolic pressure increased, in this way the blood pressure gets dropped after all.
4 Conclusions
Adrenergic drugs can increase blood pressure especially the adrenaline can increase blood
pressure apparently and isoprenaline may lead to arrhythmia. Phentolamine and propranolol both
can lower blood pressure, and Phentolamine which is α-adrenoceptor blockers act more obvious
on blood pressure. Cholinergic drugs can lower blood pressure and this ability can be reduced by
atropine which is competitive M-receptor blockers.
Reference
[1] Guo Jingyang The relationship between receptors of peripheral efferent nervous system and
the effect of drugs [J] Liaoning Medicine 1977，6(1)：24—28
Abbreviation
Ach: acetylcholine
NA：norepinephrine
Adr: adrenergic。