AJP - Regulatory, Integrative and Comparative Physiology, Vol 268, Issue 1 214-R222, Copyright © 1995 by American Physiological Society

ARTICLES

Autonomic responses of the insular cortex in hypertensive and normotensive rats

K. S. Butcher and D. F. Cechetto
Department of Stroke and Aging, John P. Robarts Research Institute, London, Ontario N6A 5K8, Canada.

Lesion and focal cerebral ischemia of the insular cortex (IC) results in elevated renal sympathetic nerve activity (RSNA) and arterial pressure (AP) in the Wistar rat, while the opposite effect is observed in the spontaneously hypertensive rat (SHR). Acute changes in AP, heart rate (HR) and RSNA were measured in propofol-anesthetized and conscious SHR (n = 17) and Wistar rats (n = 17) during pressure injection of D,L-homocysteic acid (DLH; 100 mM) and lidocaine (LID; 20 mg/ml) into the IC. DLH injections (200 nl) into the IC of anesthetized Wistar rats resulted in a significant increase in MAP (mean change = +27 +/- 7 mmHg; P < 0.05) and a significant decrease in HR (-22 +/- 9 beats/min) and RSNA (-11 +/- 4 microV.s). Neither DLH nor LID injections into the IC of anesthetized SHR affected MAP or RNA. DLH and LID injections (500 nl) into the IC of conscious Wistar rats both resulted in a significant increase in MAP (+26 +/- 5 mmHg; 11 +/- 4 mmHg, respectively). Neither DLH nor LID injections had any cardiovascular effects in the conscious SHR. It therefore appears that the IC of conscious Wistar rats has a tonic inhibitory output, while neural excitation is capable of eliciting pressor responses. Conversely, the IC of SHR appears to exert no tonic influence on MAP.

This article has been cited by other articles:

				V. G. Macefield, S. C. Gandevia, and L. A. Henderson Neural sites involved in the sustained increase in muscle sympathetic nerve activity induced by inspiratory capacity apnea: a fMRI study J Appl Physiol, January 1, 2006; 100(1): 266 - 273. [Abstract] [Full Text] [PDF]

				L. A. Henderson, C. A. Richard, P. M. Macey, M. L. Runquist, P. L. Yu, J.-P. Galons, and R. M. Harper Functional magnetic resonance signal changes in neural structures to baroreceptor reflex activation J Appl Physiol, February 1, 2004; 96(2): 693 - 703. [Abstract] [Full Text] [PDF]

				D. Sander, K. Winbeck, J. Klingelhofer, T. Etgen, and B. Conrad Prognostic relevance of pathological sympathetic activation after acute thromboembolic stroke Neurology, September 11, 2001; 57(5): 833 - 838. [Abstract] [Full Text] [PDF]

				T. Hanamori, T. Kunitake, K. Kato, and H. Kannan Responses of Neurons in the Insular Cortex to Gustatory, Visceral, and Nociceptive Stimuli in Rats J Neurophysiol, May 1, 1998; 79(5): 2535 - 2545. [Abstract] [Full Text] [PDF]

				T. M. Saleh and B. J. Connell Role of the insular cortex in the modulation of baroreflex sensitivity Am J Physiol Regulatory Integrative Comp Physiol, May 1, 1998; 274(5): R1417 - R1424. [Abstract] [Full Text] [PDF]

				T. Mizushima, F. Tajima, T. Nakamura, M. Yamamoto, K.-H. Lee, and H. Ogata Muscle Sympathetic Nerve Activity During Cold Pressor Test in Patients With Cerebrovascular Accidents Stroke, March 1, 1998; 29(3): 607 - 612. [Abstract] [Full Text] [PDF]

				K. S. Butcher and D. F. Cechetto Insular Lesion Evokes Autonomic Effects of Stroke in Normotensive and Hypertensive Rats Stroke, March 1, 1995; 26(3): 459 - 465. [Abstract] [Full Text]