The Influences Of Controlled Hypotension By Sodium Nitroprusside Or Nitroglycerin And/or Acute Normovolemic Hemodilution On The Microcirculation Of Rat

Objective To observe the influences of controlled hypotension (CH) caused by sodium nitroprusside (SNP) or nitroglycerin (NTG) and/or acute normovolemic hemodilution ( ANH) on the microcirculation of mesentery and surface of kidney and brain of rat, and to evaluate the characteristics of the two drugs during CH or CH combined with ANH.Methods 96 Wistar rats of either sex, were randomly selected for groups of mesentery (mes), kidney surface (kid) and brain surface (bra). Each of the three groups were further randomly divided to five subgroups of ANH, SNP-hypotension, NTG-hypotension, ANH combined with SNP-hypotension (SNPcom), and ANH combined with NTG-hypotension (NTGcom). Another subgroup of blank control in group of mesentery was built. Each of the subgroup contained 6 objects. The animal was anesthetized with 20% ethyl carbamate im, followed by tracheotomy, and femoral arterial and venous catheterizations were done. Then the microvasculature of mesentery, kidney and brain surface were exposed to the view of intravital microscopy. The diameter ((?)) and blood flow of the specified microvasculature were recorded and videotaped. Another blood flow value recorded was completed through laser Doppler flowmetry in kidney and brain group named LDF value. Point Intersection Count (PIC) of renal surface microcirculation was also noted. CH was achieved by continuous infusion of 0.005% SNP or NTG solution to mean arterial pressure (MAP) levels of 60 mmHg, 50 mmHg, 40 mmHg, 30~35mmHg. During ANH, target hematocrit (Hct) 25% was finished by blood extraction and meanwhile infusion of same volume of gelofusine iv. CH combined with ANH was available through ANH at first, then CH, with the same Hct and MAP as above.Results When Hct decreased to 25% by ANH, (?)mes of arterioles increased with minor extent (P<0.05), no changes in that of venules. PICkid and LDFkid value decreased significantly ( P<0.0001, 0.01, respectively). (?)bra of arterioles increased (P<0.05), while no change was found in that of venules. LDFbra value increased (P<0.05).During CH achieved by SNP or NTG, the blood flow grades of mesentery arterioles decreased significantly when MAP≤40mmHg (P<0.001). (?)mes of arterioles diminished when NTG lowed MAP≤50mmHg(P<0.05), but no change in (?)mes (including arterioles and venules) of all levels hypotension SNP induced. LDFkid value decreased significantly as MAP≤60mmHg in the two groups, and PICkid began to decline when MAP was 50mmHg (P<0.05), with the smaller slope in SNP hypotensive group of the formula describing the tendency of decreased LDFkid value. No significant change was found in (?)bra of...