13.1 Php th histamin

Dng chut lang nng 250 - 350 g. chut nhn i trong 24 gi, vn cho ung nc theo nhu cu ca chut. Git chut t ngt bng phng php thch hp.

M bng chut, dng kp, kp vo manh trng, nng ln v ko ra pha trc, s thy hi trng ni vo manh trng. Ct ly mt on hi trng di khong 2 cm, cho vo khay ng dung dch B (nu lm chm phi sc kh carbogen). Loi b cc cht cn trong on rut bng cch dng mt pipet c dung dch B lng vo u on rut ri cho dung dch B trong pipet chy t nhin qua on rut. Cn pipet t th nghing sao cho mt thong ca dung dch B khng cao qu 2 cm so vi on rut trong khay.

Thay dung dch B mi vo khay. Buc vo mi u ca on rut mt si ch mnh v rch mt ng ngang nh gia on rut.

Cho on rut vo bnh nui c quan c lp c dung tch 10 - 20 ml, cha dung dch B, v gi nhit hng nh 34 - 36oC. Sc mt hn hp kh c 95 th tch oxygen v 5 th tch carbon dioxyd qua bnh nui. Mt u si ch buc vo gn y bnh nui, u kia ni vi u ghi ca mt kimograph hoc thit b thch hp ghi s co bp ca rut. Nu dng bt ghi trn giy th iu chnh sao cho bin c th khuch i ln khong 20 ln. Sc cng ca rut nn vo khong 9,8 mN v iu chnh theo nhy ca rut.

Thay dung dch B trong bnh nui c quan. yn 10 pht. Tip tc thay dung dch B 2 - 3 ln nh vy na.

Thm vo bnh nui c quan, chnh xc khong 0,2 - 0,5 ml dung dch histamin dihydroclorid c nng nht nh gy nn mt p ng gn ti a c th lp li c. Liu ny gi l liu "cao".

Thay dung dch B bnh nui 3 ln trc mi ln thm histamin. Nn thm histamin vo nhng khong thi gian cch u rut gin hon ton gia cc ln thm (khong 2 pht).

Tng t, thm nhng th tch bng nhau ca dung dch c nng histamin thp cho p ng c bin bng khong mt na bin ca liu "cao" v c th lp li c. Liu ny gi l liu "thp".

Tip tc thm u n cc liu "cao" v liu "thp" histamin nh nu trn v xen k thm cng mt th tch dung dch pha t mu th. iu chnh pha long ca dung dch th cho sc co ca rut nh hn sc co ca liu "cao".

Kim tra xem sc co ca dung dch th c lp li khng v xem p ng vi liu cao v liu thp c nh trc khng.

Tnh hot lc ca cht th ra microgam histamin base cn c vo pha long xc nh trn. Lng histamin xc nh c khng c vt qu lng ghi trong chuyn lun.

Nu cht th khng gy co bp rut, pha mt dung dch khc v cho thm mt lng histamin ti a dung np c ghi trong chuyn lun v th vi dung dch ny. Theo di xem s co c ca dung dch ny c tng ng vi lng histamin thm khng. Nu dung dch ny khng gy ra s co c tng ng hoc s co ca dung dch th khng lp li c, hoc sau khi th cht th ri, th li vi histamin chun liu "cao" v liu "thp" m p ng co gim i th kt qu th l khng c gi tr v phi th cht h p ca thuc theo chuyn lun "Php th cc cht h p".

Dung dch A:

Natri clorid 160 g

Kali clorid 4,0 g

Calci clorid khan 2,0 g

Magnesi clorid khan 1,0 g

Dinatri hydrophosphat 50 mg

Nc ct pha tim va 1000 ml

Dung dch B:

Dung dch A 50 ml

Atropin sulfat 0,5 mg

Natri hydrocarbonat 1,0 g

D - glucose 0,5 g

Nc ct pha tim va 1000 ml

Dung dch B phi pha ngay trc khi dng v phi dng trong vng 24 gi.