James F. Szocik

Calcium current in smooth muscle cells from normotensive and genetically hypertensive rats.

Genetic hypertension results from numerous phenotypic expressions. We hypothesized that increased calcium current in vascular smooth muscle of genetically hypertensive animals is partly responsible for observed increases in agonist sensitivity, contractility, and calcium influx. Using adult, spontaneously hypertensive stroke-prone rats (SHRSP) and normotensive Wistar-Kyoto (WKY) controls from an inbred colony, we characterized calcium current in smooth muscle cells isolated from cerebral arteries. Calcium current in WKY cells reached a maximum of -27.7 +/- 2.7 pA (n = 32) at +20 mV. Peak inward current at +20 mV in SHRSP cells had a mean amplitude of -44.4 +/- 3.0 pA (n = 72, P < .05). SHRSP cells exhibited a higher calcium current density. Maximal inward current normalized to cell capacitance yielded mean values of 2.07 +/- 0.11 pA/pF for WKY (n = 32) and 2.80 +/- 0.12 pA/pF (n = 79) for SHRSP (P < .05) cells. Transient-type Ca2+ channel current had the same magnitude and current-voltage relation in both cell types, giving an L-type/T-type ratio of 3.85 for WKY and 6.25 for SHRSP cells. The voltage-dependent inactivation curve for SHRSP calcium current was shifted to the right only over the range of -50 to -30 mV, but the half-maximal inactivation voltages and Boltzmann coefficients were not significantly different between cell types. Increased calcium inward current in this model of genetic hypertension could account in part for altered calcium homeostasis and increased vascular reactivity, contributing to hypertension and vasospasm.

Inhibitory Effects of Bupivacaine and Lidocaine on Adrenergic Neuroeffector Junctions in Rat Tail Artery

Background:Various local anesthetic agents have been shown to cause relaxation of isolated vascular segments contracted by catecholamines and other constrictor drugs. This report describes the actions of the amide-linked local anesthetic, bupivacaine, on adrenergic responsiveness of isolated arterial smooth muscle, and compares bupivacaine effects with those of lidocaine Methods:Helical strips of rat tail artery mounted in a muscle bath for measurement of isometric force generation were contracted in response to adrenergic nerve stimulation, increased potassium concentration, tyramine, or exogenous norepinephrine Results:Treatment with bupivacaine or lidocaine caused depression of contraction to all four stimuli. Contraction to adrenergic nerve stimulation was more sensitive to the inhibitory effects of local anesthetics than was contraction to elevated potassium, tyramine, or exogenous norepinephrine. Furthermore, bupivacaine was more effective in reducing contraction to adrenergic nerve stimulation than was lidocaine (EC502 bupivacaine=4 X 10-6 M; lidocaine=61 X 10-6M). In arteries incubated in solutions containing [3H]-norepinephrine and mounted for supervision and isometric force recording, both bupivacaine and lidocaine (10-5 M) depressed the contractions and diminished the release of radioactivity evoked by nerve stimulation. At the concentration tested, bupivacaine was more effective than lidocaine in reducing both contraction and the efflux of radioactivity as indicated by the magnitude of depression compared with control activities. Conclusions:These findings suggest that lidocaine and bupivacaine depress adrenergic neurotransmission and inhibit smooth muscle contraction. Bupivacaine is a more potent inhibitor of adrenergic neurotransmission in the blood vessel wall than is lidocaine

Impact of a cost containment program on the use of volatile anesthetics and neuromuscular blocking drugs

Study Objective: To determine the impact of a cost containment program on the use of volatile anesthetics and neuromuscular blocking drugs. Design: Historical, controlled, retrospective analysis. Setting: Main operating rooms of an adult general hospital at a university medical center. Patients: All patients undergoing anesthesia between July 1991 and November 1993. Measurements and Main Results: Cost per case was determined by dividing the monthly expediture for each class of drug by the caseload for that month. Cost per case of volatile anesthetic drugs decreased from

Fundamental Principles of Monitoring Instrumentation

19.20 ± 1.16 to

Temporary facial nerve palsy during carotid endarterectomy under local anesthesia

15.16 ± 0.39 ( p = 0.0034 by unpaired t -test). For neuromuscular blocking drugs, cost per case decreased from

Interaction of chick oviduct progesterone receptor with sodium tungstate: Inhibition of activation and DNA binding

19.67 ± 1.35 to

pH-dependent effects of sodium tungstate on the steroid-binding properties of hen oviduct progesterone receptor

12.23 ± 0.66 ( p = 0.003). Conclusions: Concerted educational efforts can decrease the per case expenditures for both volatile anesthetic drugs and neuromuscular blocking drugs.

Overview of Clinical Monitoring

• Accuracy and precision are different. Accuracy is how close a value is to the true value. Precision is how repeatable the measurements are. An inaccurate but precise monitor can be recalibrated to be accurate, but an imprecise monitor cannot be improved. • Filtering can improve the signal display, but it can also result in smoothing and a loss of information. • A signal can be extracted from noise by repeated measurements, because the noise is random over time but the signal is not. • Electrical signals can be converted from analog to digital. Conversion can introduce some artifacts but can allow for greater storage and analysis capabilities. • Invasive pressure monitors are affected by damping and resonance. Damping leads to distortion, signal loss, and lowering of peak values. Resonance can lead to amplification and overestimation of the peak value. • Pulse oximetry combines analysis of optical plethysmography and absorption analysis with empirical data to produce an estimate of arterial oxygen saturation (Sao2). • Wavelength and frequency are related to the speed of the wave by the following formula: speed = wavelength × frequency. Shorter wavelengths improve the resolution of both light and ultrasound measurements. • Flow measurements are one of the most difficult to obtain and usually involve indirect measures. (For example, a temperature change or pressure drop is measured and a flow value is derived. A small error in the initial measurement leads to a much larger error in the derived flow value.)

Ethics, continuing medical education, industry, and anesthesia.

T he cervical plexus block can be advantageous for carotid endarterectomy, allowing the anesthesiologist and surgeon to monitor the neurologic status of the patient. On occasion, inadequate blockade necessitates a change of technique to either local infiltration or general anesthesia. We report a case of temporary facial nerve palsy during a carotid endarterectomy performed under regional anesthesia supplemented with local anesthetic after inadequate cervical plexus blockade.

Impact of a Cost Containment Program on the Use of Volatile Anesthetics and Neuromuscular Blocking Drugs

Abstract The effects of sodium tungstate on the chick oviduct progesterone receptor were examined and found to be pH-dependent. When freshly prepared cytosol receptor preparations were activated by incubation at 23°C in presence of different concentrations of sodium tungstate, receptor activation was completely blocked by 0.2 and 2 mM inhibitor at pH 7 and pH 8, respectively. The presence of tungstate inhibited the maximum extent and not the rate of activation. DNA-cellulose binding of the activated cytosol receptor was also inhibited completely by 2.5 mM tungstate at pH 7, whereas at pH 8, no significant inhibition was observed with up to 10 mM tungstate. Tungstate was more effective in blocking the DNA binding when (NH4)2SO4-fractionated receptor was used, causing a complete inhibition by 1 and 10 mM at pH 7 and pH 8, respectively. The effect of tungstate on the DNA binding of activated receptor appeared specific while several other phosphatase inhibitors were less or completely ineffective. Upon its adsorption onto DNA-cellulose, the receptor could be extracted in a specific manner by 0.2 and 2 mM tungstate at pH 7 and pH 8, respectively. The tungstate-extracted receptor sedimented in ihe 4.3–6S region in high- (0.3 M KCl) and low-salt (10mM KCl) sucrose gradients. Following the incubation with/or extraction from DNA-cellulose with tungstate, the DNA binding capacity of the receptor was completely lost and could not be recovered upon dialysis. In contrast to effects of previously more thoroughly studied molybdate ions, tungstate affects both the non-activated and activated progesterone receptor. The effects of tungstate appear direct and due to its interaction with the progesterone receptor and may not involve a mere inhibition of phosphatase activities in the receptor preparations.