Concerning the heart function during copulation in mammalian, there are few reports on dogs and human such as the heart rate shows a remarkable increasing toward the orgasm. In large domestic animals, however, no observation of heart rate during copulation have been reported nevertheless their sexual behaviour have been well described on several textbooks. Since recent development of medical electronics, it become capable to obtain easily several physiological informations in physiology and clinical medicine using of telemetric techniques. Electrocardiographical change during excercise in race horses have been reported by several authors. From their investigations, heart rate change in various stages of excercise have been demonstrated clearly as well as in changes of ECG pattern. In the present experiment, a set of radioelectrocardiograph (Fukuda Denshi Co. Tokyo) and a plate type electrode designed by TOO et al (1967) were used. Experimental animals used in this investigation were Percheron stallion (7 years old) and Thoroughbred stallion (9 years old) respectively. A bipolar lead (Apex-Base) was applied for taking ECG through the whole course of the copulation. From ECG tracings, changes of heart rate and ECG pattern following male sexual behaviour were studied.
In Percheron stallion, 6 trials of copulation were recorded. Heart rate in resting state which the stallion staying in the stable was counted as 30-40 per minute. When the stallion moves to place for mating where fence around from the stable and walks surround female in the place, the heart rate showed about 70 per minute. During courtship, remarkable fluctuation of heart rate with severe irregularity was observed.This due to sniffing of the stallion and thought to be effected by deep inspiration. Starting the mounting, the heart rate showed sudden increase within short time (15-45 sec.) and it rearched to 150-170 per minute, which is comparable to 70 per minute as a before value. By this time, intromission of the penis and pelvic oscillation are included. Soon after the ejaculation was seen. Duration between start of mounting to the ejaculation was variable ranged with 35-57 seconds. The shortest R-R interval was recorded in every 6 trials at the ejaculation or between the ejaculation to dismounting. The shortest R-R interval was maintained for 35 seconds. After dismounting the heart rate decreased rapidly until the heart rate rearches to a level of about 120 per minute. Then the heart rate gradually decreased toward the value of resting state. It needed about 3-10 minutes for recover from higher level to near value in resting stage. Length for recover from higher level was varied by a condition of the stallion after copulation. When the stallion was less excitability the heart rate return to before value within short time, in contrast, however, when the stallion was excite himself again the time was prolonged. A typical diagram of the heart rate change is shown in the figure. Ventricular extrasystoles at mounting and soon after dismounting, changes of T wave with high amplitude parallel with tachycardia and elevation of ST-T were respectively observed.
In Thoroughbred stallion, only one trial was carried out. Heart rate at resting state in stable was less than 60 per minute. When a mare gives a loud neigh at distant place, the heart rate of the stallion increased temporary to 130 per minute. After then the stallion started to place for mating. In the place, facing to the female, the stallion showed remarkable excitability, the heart rate increased rapidly to peaked value of 170-180 per minute. After the peak, the heart rate decreased gradually and the mounting was done at 115 per minute of the heart rate. The value increased slightly to 130 per minute by mounting and followed ejaculation. After dismounting, the heart rate decreased 80 per minute.

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The authors tried to clarify the heart sound of calf and cattle as a basic study of the phonocardiogram (PCG) and calculate each wave of PCG. A PCG was recorded from five sites on the body surface, which were the apical site and pulmonic, aortic, mitral, and tricuspid areas, in fifteen healthy calves and five cattles.
Recording was made by a two-channel recorder at a paper speed of 50 or 100mm/sec.
A frequency filter was set at L (under 50 Hz) and M₁ (50-80 Hz).
A microphone of MA-280 type (35g, 25φx 8mm), which was made by the Fukuda Electronic Co., Ltd., was used.
The PCG's records were analyzed for the following factors : pattern of PCG, duration of first (S₁) and second (S₂) heart sound, Q-S₁ and Q-S₂ interval, amplitude ratio (S₂/S₁), and frequency of S₁ and S₂.
1) All the patterns of S₁ were of crescend-decrescend type and those of S₂ of crescenddecrescend and decrescend types in both calves and cattle.
2) The duration of S₁ was calculated to be 0.13 (0.12-0.14) sec. in the calves and 0.15 (0.14-0.17) sec. in the cattle when the L filter was used. It was 0.12 (0.11-0.13) sec. in the calves and 0.14 (0.13-0 15) sec. in the cattle when M₁ filter recording was made.
3) The duration of S₂ was calculated to be 0.08 (0.07-0.08) sec. in the calves and 0.08 (0.07-0.09) sec. in the cattle when the L filter was used. It was 0.07 (0.07-0.08) sec. in both calves and cattle in the M₁ filter recording.
4) The Q-S₁ interval was calculated to be 0.04 sec. in the calves and 0.05 sec. in the cattle in both L and M₁ filter recording.
5) The Q-S₂ interval was calculated to be 0.37 (0.36-0.38) sec. in the calves and 0.41 (0.40-0.44) sec. in the cattle in L filter recording, and 0.38 (0.38-0.38) sec. in the calves and 0.41 (0.40-0.41) sec. in the cattle in M₁ filter recording.
6) The amplitude ratio (S₂/S₁) ranged from 0.6 to 1.2 in the calves and from 0.4 to 0.9 in the cattle in L filter recording, and from 0.9 to 1.5 in the calves and from 0.6 to 1.1 in the cattle in M₁ filter recording.
7) The frequecy of S₁ was calculated to be 40 (38-47) Hz in the calves and 40 (37-43) Hz in the cattle in L filter recording, and 53 (50-60) Hz in the calves and 51 (50-54) Hz in the cattle in M₁ filter recording.
8) The frequency of S₂ was calculated to be 40 (39-46) Hz in the calves and 45 (40-50) Hz in the cattle in L filter recording, and 56 (53-66) Hz in the calves and 57 (50-63) Hz in the cattle in M₁ filter recording.

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Six female Rhesus monkeys, 7-9 years old and 4.0-7.5 kg in body weight, were used for research on the thoracic morphology and the cardiac position in the thorax by gross anatomical studies and X-ray observations.
The results were as follows;
1. The thoracic index in Rhesus monkeys are about 115-125. The shape of the thorax in the Rhesus monkey is more similar to that of dogs' than that of mans'.
2. The cardiac axis inclines at 35°to the sagittal plane from the ventral view, and 25°to the sternum from the lateral view.
3. The heart is located between the third rib and the sixth intercosta. The cardiac position in the thorax shows almost no change according to changes of physical conditions or the movement of the forelimb, from X-ray observations.
4. The perpendicular line to the horizontal plane and parallel to the sagittal plane from both nipples run through the right and left ventricles in all cases. Also the position of the nipples shows almost no change as with the cardiac position.
Therefore, it is presumed that the nipples are standard points for determining the cardiac position from the surface of the chest.

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The effects CS-359 (5-methyl-8-(2-hydroxy-3-t-butylaminopropoxy) coumarin hydrochloride), a new β-adrenergic blocking agent, on positive chronotropic responses to Isoproterenol and exercise were compared with those of Propranolol in conscious beagle dogs. The heart rate was measured from the electrocardiogram ABL-I recorded with biopotential skin electrodes. Exercise was performed for 3 min on a motor-driven treadmill. Heart rate rose rapidly at first and then stabilized at a certain level making a plateau. The level of heart rate in the plateau was in parallel with amount of the exercise within a range from 90 to 200 m/min. l-Isoproterenol (0.2μg/kg) was administered through an indwelling cannula in the ear vein. Following oral administration of a β-adrenergic blocking agent, each animal received Isoproterenol or treadmill exercise at 30 or 60 min intervals for 6 hr. Dose-response curves for β-adrenergic blocking activity against Isoproterenol tachycardia revealed that CS-359 was 2 to 3 times more potent than Propranolol. Similar results were obtained in preventing Exercise tachycardia; e. g., 0.3 mg/kg of CS-359 and 1.0 mg/kg of Propranolol equally inhibited the tachycardia. The tachycardia induced by exercise, however, could not be completely prevented even by the treatment with an extremely high dose of β-adrenergic blocking agents, while Isoproterenol tachycardia was abolished by a sufficient high dose of the blockers. Therefore, Exercise tachycardia may partly be attributed to the inhibition of vagal tone. Experiments with β-adrenergic, parasympathetic and combined blockades also supported the contribution of the vagal inhibition.

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