Pancreatic islet blood flow in conscious rats during hyperglycemia and hypoglycemia

2001 ◽  
Vol 280 (6) ◽  
pp. R1601-R1605 ◽  
Author(s):  
M. Iwase ◽  
K. Tashiro ◽  
Y. Uchizono ◽  
D. Goto ◽  
M. Yoshinari
Keyword(s):  
Blood Flow ◽  
Pancreatic Islet ◽  
Organ Perfusion ◽  
Pancreatic Blood Flow ◽  
Pentobarbital Sodium ◽  
Time Points ◽  
Conscious Rats ◽  
Colored Microspheres ◽  
Islet Blood Flow ◽  
Anesthetized Rats

Anesthesia affects general hemodynamics and regulation of organ perfusion. We used colored microspheres to measure pancreatic islet blood flow in conscious rats at two time points, during either hyperglycemia or hypoglycemia. This method, using black and green microspheres, was validated by comparison with previous microsphere experiments and by lack of effect of a nonmetabolizable glucose analog, 3- O-methylglucose, on islet perfusion. Basal and glucose-stimulated islet blood flow levels were similar in pentobarbital sodium-anesthetized and conscious rats. However, the basal distribution of pancreatic blood flow was altered by anesthesia (fractional islet blood flow 5.8 ± 0.4% in conscious rats, 7.9 ± 0.8% in pentobarbital-anesthetized rats, P < 0.05). Insulin-induced hypoglycemia significantly increased whole pancreatic blood flow in conscious rats, whereas islet blood flow remained unchanged and fractional islet blood flow was decreased (5.8 ± 0.5% in the basal state, 4.2 ± 0.4% during hypoglycemia, P < 0.001). Methylatropine pretreatment significantly increased islet blood flow during hypoglycemia by 181%. This result suggests that prevention of hypoglycemia-induced increase in islet perfusion may be mediated, at least in part, by a cholinergic, vagal muscarinic mechanism.

scholarly journals KATP Channels and Pancreatic Islet Blood Flow in Anesthetized Rats: Increased Blood Flow Induced by Potassium Channel Openers

Diabetes ◽  
2003 ◽  
Vol 52 (8) ◽  
pp. 2043-2048 ◽  
Author(s):  
L. Jansson ◽  
M. Kullin ◽  
F. A. Karlsson ◽  
B. Bodin ◽  
J. B. Hansen ◽  
...  
Keyword(s):  
Blood Flow ◽  
Potassium Channel ◽  
Pancreatic Islet ◽  
Katp Channels ◽  
Potassium Channel Openers ◽  
Islet Blood Flow ◽  
Anesthetized Rats ◽  
Increased Blood Flow

Blood lipids affect rat islet blood flow regulation through β3-adrenoceptors

2014 ◽  
Vol 307 (8) ◽  
pp. E653-E663 ◽  
Author(s):  
Enyin Lai ◽  
Ulrika Pettersson ◽  
Alberto Delgado Verdugo ◽  
Per-Ola Carlsson ◽  
Birgitta Bodin ◽  
...  
Keyword(s):  
Blood Flow ◽  
Pancreatic Islet ◽  
Blood Lipids ◽  
Parasympathetic Nervous System ◽  
Serum Insulin ◽  
Insulin Response ◽  
Simultaneous Increase ◽  
Acute Administration ◽  
Islet Blood Flow ◽  
Anesthetized Rats

Pancreatic islet blood perfusion varies according to the needs for insulin secretion. We examined the effects of blood lipids on pancreatic islet blood flow in anesthetized rats. Acute administration of Intralipid to anesthetized rats increased both triglycerides and free fatty acids, associated with a simultaneous increase in total pancreatic and islet blood flow. A preceding abdominal vagotomy markedly potentiated this and led acutely to a 10-fold increase in islet blood flow associated with a similar increase in serum insulin concentrations. The islet blood flow and serum insulin response could be largely prevented by pretreatment with propranolol and the selective β3-adrenergic inhibitor SR-59230A. The nitric oxide synthase inhibitor NG-nitro-l-arginine methyl ester prevented the blood flow increase but was less effective in reducing serum insulin. Increased islet blood flow after Intralipid administration was also seen in islet and whole pancreas transplanted rats, i.e., models with different degrees of chronic islet denervation, but the effect was not as pronounced. In isolated vascularly perfused single islets Intralipid dilated islet arterioles, but this was not affected by SR-59230A. Both the sympathetic and parasympathetic nervous system are important for the coordination of islet blood flow and insulin release during hyperlipidemia, with a previously unknown role for β3-adrenoceptors.

Role of site of microsphere injection and catheter position on systemic and regional hemodynamics in rat

1984 ◽  
Vol 247 (1) ◽  
pp. H35-H39 ◽  
Author(s):  
I. Kobrin ◽  
M. B. Kardon ◽  
W. Oigman ◽  
B. L. Pegram ◽  
E. D. Frohlich
Keyword(s):  
Blood Flow ◽  
Coronary Blood Flow ◽  
Coronary Flow ◽  
Left Ventricular ◽  
Ventricular Catheter ◽  
Catheter Position ◽  
Flow Measurements ◽  
Conscious Rats ◽  
Anesthetized Rats ◽  
Regional Hemodynamics

The influences of the site of microsphere injection (intra-atrial vs. intraventricular) and positioning of the left ventricular catheter (aortoventricular vs. atrioventricular) on systemic, renal, and coronary hemodynamics were evaluated in anesthetized rats. The effect of anesthesia on aortoventricular catheter positioning was also evaluated. In anesthetized and open-chest preparations, the systemic and renal hemodynamics were not affected by catheter position or site of microsphere injection; however, myocardial blood flow was dependent on these variables. Variations in coronary blood flow were significantly greater when the catheter was in the aortoventricular position (34 +/- 3%) than with an atrioventricular catheter (11 +/- 2%, P less than 0.01), irrespective of whether the microspheres were injected into the atrium or ventricle. Comparison of anesthetized and conscious rats with aortoventricular catheter indicated lesser variability in coronary blood flow in the conscious rats (P less than 0.01). Therefore, the greater variability of coronary flow measurements in anesthetized rats was caused by the position of the cardiac catheter in the aortoventricular route. However, the variability caused by the aortoventricular catheter was much less in conscious rats. Therefore, coronary flow hemodynamic measurements (microsphere technique) are less variable when they are made in conscious rats.

The 400 microsphere per piece “rule” does not apply to all blood flow studies

2000 ◽  
Vol 278 (1) ◽  
pp. H16-H25 ◽  
Author(s):  
Nayak L. Polissar ◽  
Derek C. Stanford ◽  
Robb W. Glenny
Keyword(s):  
Blood Flow ◽  
Close Agreement ◽  
Animal Experiment ◽  
Correlation Coefficients ◽  
Poisson Noise ◽  
Good Precision ◽  
Organ Perfusion ◽  
Time Points ◽  
Rule Of Thumb ◽  
Single Region

Microsphere experiments are useful in measuring regional organ perfusion as well as heterogeneity of blood flow within organs and correlation of perfusion between organ pieces at different time points. A 400 microspheres/piece “rule” is often used in planning experiments or to determine whether experiments are valid. This rule is based on the statement that 400 microspheres must lodge in a region for 95% confidence that the observed flow in the region is within 10% of the true flow. The 400 microspheres precision rule, however, only applies to measurements of perfusion to a single region or organ piece. Examples, simulations, and an animal experiment were carried out to show that good precision for measurements of heterogeneity and correlation can be obtained from many experiments with <400 microspheres/piece. Furthermore, methods were developed and tested for correcting the observed heterogeneity and correlation to remove the Poisson “noise” due to discrete microsphere measurements. The animal experiment shows adjusted values of heterogeneity and correlation that are in close agreement for measurements made with many or few microspheres/piece. Simulations demonstrate that the adjusted values are accurate for a variety of experiments with far fewer than 400 microspheres/piece. Thus the 400 microspheres rule does not apply to many experiments. A “rule of thumb” is that experiments with a total of at least 15,000 microspheres, for all pieces combined, are very likely to yield accurate estimates of heterogeneity. Experiments with a total of at least 25,000 microspheres are very likely to yield accurate estimates of correlation coefficients.

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