Left ventricular performance during spontaneous exercise has been continuously analyzed in terms of direct recordings of diameter, effective pressure and other parameters derived by electronic computors. The changes in left ventricular performance during treadmill exercise have been compared with a number of experimentally induced responses in the same intact unanesthetized dog on the same day. These direct comparisons revealed that experimentally-induced increased venous return, reduced peripheral resistance, or administration of autonomic hormones do not reproduce the spontaneous exercise response. Better reproductions of the exercise response could be achieved by careful administration of isopropyl arterenol (Isuprel), by combined administration of epinephrine or norepinephrine) and experimental tachycardia or by stimulating sympathetic nerves to the heart. Stimulation of discrete areas in the diencephalon reproduced the exercise response with remarkable accuracy without movement or evidence of distress.

Smith OA, Astley CA. Naturally occurring hypertension in New World nonhuman primates: potential role of the perifornical hypothalamus. Am J Physiol Regul Integr Comp Physiol 292: R937-R945, 2007. First published October 5, 2006; doi:10.1152/ajpregu.00400.2006.-Hypertension is a prominent underlying factor in the genesis of cardiovascular-related morbidity and mortality. A major impediment to the investigation into the causes of the disease is the paucity of naturally occurring animal models of the disease. There is evidence that some species of New World primates spontaneously become hypertensive. We used chronically implanted pressure transducers to assess normally occurring blood pressure and heart rate levels at rest and during routine laboratory procedures in a group of one of these New World primates (Aotus sp.). Resting mean arterial pressure ranged from 72 to 130 mmHg. Three animals were judged to have resting mean arterial pressure levels in the hypertensive range (Ն110 mmHg). In all of the animals, pressor responses to routine laboratory events were exaggerated (average highest mean pressure during 1 min from any session was 97-196 mmHg). Subsequently, the region of the perifornical/lateral hypothalamus known to produce elevated blood pressure and heart rate responses to electrical stimulation was removed, and the blood pressure responses to the laboratory routines were significantly decreased and, in some cases, eliminated. Control lesions in nearby tissue had no effect on these responses. This region may play a critical role in initiating or exacerbating cardiovascular responses that contribute to the development of essential hypertension. essential hypertension; environment; perifornical/lateral hypothalamus TWO SPECIES of New World monkeys, the "woolly" (Lagothrix lagotricha) and the "owl" (Aotus sp.) monkey, are potentially valuable models of naturally occurring hypertension. These species came to our attention because of the elevated rates of cardiovascular (CV)-related mortality of these monkeys in captivity and the subsequent pathological findings. The woolly monkeys show hyaline arteriolar nephrosclerosis, one of the earliest histological changes associated with hypertension in humans (7), and the Aotus shows cardiomegaly and cardiomyopathy (8, 27), which are also associated with hypertension in humans. The causes of the mortality in these animals include stroke, renal failure, aortic aneurysm rupture, and congestive heart failure, all of which are strongly suggestive of hypertensive disease.To follow up on these observations, we performed preliminary surveys on both species by direct measurement of blood pressure via arterial puncture. The animals were under ketamine sedation, and the pressures in most animals exceeded the accepted "normal" blood pressure levels for primates. Many of the levels were excessively high. The results of the study of the woolly monkeys in zoos and in private hands have been reported elsewhere (7). The survey of the owl monkeys took place at the Battelle Pacific Nort...

We did four experiments to determine whether the lateral hypothalamus-perifornical (LH/PF) region is the source of neuronal cell bodies responsible for producing the cardiovascular (CV) responses associated with emotion or the defense reaction. Of particular concern was whether the paraventricular nucleus (PVN) plays a role in the generation of these CV responses. Mapping the hypothalamus with electrical stimulation showed that the CV pattern of responses was never produced by stimulating the PVN and was invariably produced by stimulating the LH/PF region. Complete electrolytic destruction of the PVN and subsequent axonal degeneration did not change the CV pattern of responses elicited by LH/PF stimulation, whereas any encroachment of the lesion on the LH/PF region decreased the magnitude of the CV responses. Injection of the neuroexcitotoxin ibotenic acid (Ibo) into the PVN did not affect responses to LH/PF stimulation, whereas Ibo injection into the LH/PF region eliminated or severely attenuated the CV responses. Retrograde labeling of cells from the thoracic cord and the ventrolateral reticular formation revealed a scattered group of cells in the LH/PF region that may be the cells controlling the CV responses. These results point directly to the LH/PF region as the source of the cell bodies responsible for the autonomic responses associated with emotion or defense reactions.

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