ORIGINAL ARTICLES   

Panminerva Medica 1998 December;40(4):280-5

Copyright © 2000 EDIZIONI MINERVA MEDICA

language: English

Loss of endothelium mediated vascular relaxation as a response to various clamping pressure. Part I. A pharmacological study

Gersak B., Trobec R.*, Krisch I.**

From the Department of Cardiovascular Surgery, Medical Centre Ljubljana * Jozef Stefan Institute, Ljubljana ** LEK Pharmaceutical Company, Ljubljana, Slovenia

Back­ground. The con­trac­tion/relax­a­tion ­response of tho­rac­ic aor­tal ­rings ­clamped ­with two clamp­ing pres­sures to KCl, nor­a­dren­a­line and car­ba­chol was stud­ied.
Meth­ods. ­Clamp A had the tip pres­sure PA=0.60 N/mm2 and ­clamp B PB=5.16 N/mm2. In fif­teen ­Wistar albi­no ­rats, weigh­ing 328±19 g (­mean ±SD) the tho­rac­ic aor­ta was occlud­ed for 15 min­utes and ­then ­three vas­cu­lar ­rings (2 mm ­wide) ­were ­excised. The prox­i­mal ­unclamped ­ring ­served as a con­trol. ­From dis­tal ­rings the diam­e­ter of the aor­ta was cal­cu­lat­ed ­from ­their cir­cum­fer­ence 1.61±0.01 mm (n=15, ­dmin=1.51 mm, ­dmax=1.70 mm). The ­rings ­were chal­lenged ­with cumu­la­tive addi­tions of KCl (10-80 ­mmol/l) to meas­ure the con­trac­tion. ­Then cumu­la­tive relax­a­tion to car­ba­chol (0.01-100 µmol/l) as a ­response to nor­a­dren­a­line pre­con­trac­tion (0.1 µmol/l) was deter­mined.
­Results. A sig­nif­i­cant ­loss (p<0.05) of vas­cu­lar relax­a­tion in all ­clamped ­rings (­clamped ­with PA and PB clamp­ing pres­sures) was ­seen. No sig­nif­i­cant dif­fer­enc­es (p>0.05) ­were ­observed for con­trac­tion ­between ­clamped and con­trol ­rings ­clamped ­with ­clamp A, how­ev­er the ­rings ­clamped ­with ­clamp B ­showed a sig­nif­i­cant reduc­tion in con­trac­tion (p<0.05). No sig­nif­i­cant dif­fer­enc­es ­were ­seen ­from con­trol ­rings ­between ­groups A and B (p>0.05), or ­from ­clamped ­rings ­between ­groups A and B (p>0.05) for ­both the con­trac­tion and relax­a­tion ­part of experi­ments.
Con­clu­sions. Endo­the­lial vas­cu­lar ­layers are ­much ­more sus­cep­ti­ble to pres­sure inju­ries ­than was pre­vi­ous­ly ­believed.