Objective: Patients with reduced nonlinear component of heart rate regulation show a poor prognosis. We previously reported that the linear correlation between renal sympathetic nerve activity(RSNA) and blood pressure(BP) or RSNA and renal blood flow(RBF) was significantly higher and the nonlinear correlation was lower in spontaneously hypertensive rats(SHR) than in Wistar-Kyoto rats. In the present study, we examined whether the linear and nonlinear correlation between RSNA and BP or RBF would change in SHR orally treated with angiotensin IIreceptor blocker(candesartan) or calcium channel blocker(amlodipine) for 2 weeks. Also, to elucidate mechanisms underlying the reduced linearity by amlodipine, we examined whether the linear and nonlinear correlation between RSNA and BP or RBF would change in SHR treated with amlodipine and L-NAME orally for 2 weeks.
Methods: By recording BP, RSNA, heart rate, and ipsilateral RBF simultaneously in conscious state, we compared the linear(coherence of transfer function) and nonlinear(mutual information method) correlations among RSNA, BP and RBF in SHR treated with drugs.
<Protocol 1> Candesartan(1mg/kg/day, n=13), amlodipine(5mg/kg/day, n=7) or vehicle (n=7) was given orally for 2 weeks to SHRs.
<Protocol 2> Combination of amlodipine(5mg/kg/day) and L-NAME(1.5mg/kg/day, n=9), amlodipine(5mg/kg/ day, n=7), or vehicle was given orally for 2 weeks to SHRs.
Results: <Protocol 1>Mean RSNA was significantly decreased in the candesartan group despite lower BP and larger RBF, whereas RSNA did not decrease in the amlodipine group. The coherence between RSNA and BP or between RSNA and RBF at 0-1.0 Hz was significantly reduced in both candesartan and amlodipine groups compared with vehicle group. In contrast , mutual information of the correlation between RSNA and BP or RSNA and RBF increased in both candesaratan and amlodipine groups. <Protocol 2> The coherence between RSNA and BP or RBF was significantly higher and mutual information was lower in SHR treated with amlodipine plus L-NAME compared with SHR treated with only amlodipine.
Conclusions: The data regarding candesartan suggest that blockade of the renin-angiotensin system and sympathetic nervous system contributes to the reduced linearity and increased nonlinearity. However, since this is not the case with amlodipine, increased nitric oxide contributed to the improved neural regulation by the calcium channel blocker. Since potentiated sympathetic nerve activity and high linearity/low nonlinearity are risk factors for cardiovascular events, drugs that reduce sympathetic nerve activity and normalize the neural regulation are beneficial to prevent cardiovascular events in hypertensive patients.

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Levobupivacaine is a long acting, amide-type local anaesthetic that is the S(−)-isomer of the racemate bupivacaine. It has high affinity for the myocardial Na⁺ channel that can be cardiotoxic. So, an intravenous injection of levobupivacaine sometimes becomes a serious problem as the inhibition of cardiac function.
Then, we investigated the effects of cardiac pacing and catecholamines(epinephrine, norepinephrine, isoproterenol) to treat the inhibition of cardiac function in isolated rat hearts.
Our results showed that cardiac pacing and 0.8μg/kg/min epinephrine recovered the inhibition of cardiac function due to 5μg/ml levobupivacaine.

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Transesophageal echocardiography(TEE) was used for 18 patients undergoing the internal thoracic artery to the left anterior descending artery bypass grafting on beating heart between October 1999 and May 2000. Patients were aged from 58 to 79, averaged 68.1 years old. Gender was 13 in male. There were no significant differences in the effects of placement of two types of stabilizer, CTS and Octopus2, on left ventricular inter-nal diameter in diastole and systole, end diastolic volume, end systolic volume, ejection fraction, and cardiac output. However, peak systolic meridional wall stress(PSS) tended to reduce in patients without an intraluminal shunt tube as compared with those with the tube. Therefore, intraluminal shunt tube seems to be effective to avoid regional ischemic stress. TEE would be a useful monitor of the left ventricular performance during the off pump CABG.

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