13.3 Php th cc cht h p

Th cc cht h p l phng php sinh hc da vo tc dng h huyt p ca thuc em th trn mo c gy m so vi hot lc ca thuc histamin chun.

Chun b th nghim

ng vt: Mo kho mnh, trng thnh, c hoc ci (khng mang thai), cn nng t 1,8 kg tr ln.

Nc mui heparin: Dung dch cha 50 n v heparin trong 1ml dung dch natri clorid 0,9% dng chng ng mu. C th dng mt dung dch chng ng thch hp thay th.

Dung dch histamin chun: Dng histamin dihydroclorid hoc histamin hydrophosphat bo qun trong l kn, lm kh bng silicagel 2 gi trc khi cn. Ho tan trong nc ct mt lng histamin c cn chnh xc, sau pha long bng dung dch natri clorid 0,9% tit khun thnh dung dch c nng 0,1 mg/ml tnh theo histamin base.

Mu th: Pha theo tng chuyn lun tng ng trong dung dch natri clorid 0,9% tit khun hoc trong dung mi thch hp, n nng cn thit.

Tin hnh

Mo c gy m bng cloralose hoc mt loi barbiturat thch hp nh phenobarbital v.v. duy tr c huyt p ng u trong sut thi gian th nghim. C nh ng vt trn bn m, cn lm nh nhng sao cho mo khng b kch thch. C bin php gi thn nhit mo khng gim qu gii hn sinh l bng n hoc l si. Thng kh qun bng mt canun thu tinh. Bc l ng mch cnh, lng canun c cha y nc mui heparin (hoc dung dch chng ng khc) vo ng mch cnh. Ni canun vi huyt p k thu ngn hoc mt thit b ghi huyt p khc t yu cu v nhy. Bc l tnh mch i, lun vo mt kim tim u t c cha nc mui heparin, buc c nh li tim mu th hoc histamin chun.

Xc nh nhy ca ng vt vi histamin bng cch tim tnh mch cc liu 1 ml (0,1mg v 1,5 ml (0,15 mg) dung dch histamin chun cho mi kg th trng. Khong cch thi gian gia cc ln tim t nht l 1 pht sau khi huyt p tr li mc bnh thng. Bnh thng mt liu histamin 0,1mg/kg th trng mo lm huyt p h khong 20 mmHg. Lp li liu thp histamin chun (1 ml/ kg) t nht 2 ln. ng vt c dng vo th nghim khi s gim huyt p l hng nh cc liu 1 ml/ kg v vi liu 1,5 ml/ kg phi c h p ln hn.

Sau khi t yu cu th nhy vi histamin, tim tnh mch cho mi kg mo 1 ml dung dch histamin chun. Tip theo tim 2 liu lin tc ca mu th theo ch dn ca tng chuyn lun v cui cng li tim dung dch histamin chun vi liu 1 ml/ kg. Thi gian gia cc ln tim l hng nh nh nu trn. Nhc li chui tim nh trn mt ln na v kt thc bng 1,5 ml dung dch histamin chun cho 1 kg mo.

nh gi kt qu

a. Nu h p ca dung dch histamin chun liu 1,5 ml/ kg khng ln hn liu 1 ml/ kg th th nghim khng c gi tr.

b. Ch phm t yu cu v th cc cht h p nu t c 2 iu kin sau:

Gi tr trung bnh ca cc h p khi tim mu th khng ln hn gi tr trung bnh ca cc h p khi tim dung dch histamin chun liu 1 ml/ kg th trng mo.

Mc h p ca mi ln tim mu th u khng cao hn mc h p ca dung dch histamin chun liu kt thc 1,5 ml/kg.

c. Ch phm khng t yu cu nu mt trong 2 iu kin trn khng t.

Ch : ng vt khng c dng th tc dng h p na nu trong qu trnh th, c ln mu th gy h p ln hn mc h p do liu kt thc 1,5 ml dung dch histamin chun cho 1 kg mo, hoc gi tr h p ca dung dch histamin chun liu kt thc 1,5 ml/ kg nh hn gi tr trung bnh ca cc liu 1 ml/ kg tim trc .