In vivo detection of endogenous XXXX release in cat ventricles.

@entity4033 @entity1617 @entity2607 @entity468 @entity934
To detect and monitor endogenous @entity934 ( @entity1617 ) release in the in vivo heart, we applied a dialysis technique to the hearts of anesthetized @entity468 . Dialysis probes were implanted in the left ventricular myocardium and were perfused with Krebs-Henseleit solution containing @entity2607 (10(-4) M) at 3 microliters/min. Dialysate @entity1617 concentration was measured with high-performance liquid chromatography. In four @entity468 , the response to vagal stimulation was studied. Electrical stimulation of efferent vagal nerves (10 Hz) significantly increased dialysate @entity1617 concentration from 596 +/- 118 (control) to 12,210 +/- 1,661 pM. After stimulation, dialysate @entity1617 concentration significantly decreased to 382 +/- 80 pM below control. The influence of ganglionic blocker was determined in six @entity468 . Control vagal nerve stimulation (10 Hz) increased dialysate @entity1617 concentration from 582 +/- 136 to 9,102 +/- 754 pM. Local perfusion of @entity4033 (10(-4) M) did not affect this nerve stimulation-induced @entity1617 increase (8,611 +/- 1,189 pM), and intravenous administration of @entity4033 (20 mg/kg) prevented this increase (340 +/- 88 pM). We examined the response to vagal nerve stimulation at different frequencies in three @entity468 . Vagal nerve stimulation increased dialysate @entity1617 concentration from a control of 588 +/- 211 to 1,227 +/- 195 pM at 2 Hz, 3,946 +/- 1,059 pM at 5 Hz, and 9,366 +/- 1,873 pM at 10 Hz. Dialysate @entity1617 concentration reflects @entity1617 release from postganglionic vagal nerves innervating the left ventricular myocardium; the dialysis technique permits estimation of relative changes in efferent cardiac vagal nerve activity.
